diff --git a/.editorconfig b/.editorconfig new file mode 100644 index 0000000000..db6f34c77c --- /dev/null +++ b/.editorconfig @@ -0,0 +1,14 @@ +root = true + +[*] +indent_style = space +indent_size = 2 +charset = utf-8 +trim_trailing_whitespace = true +insert_final_newline = true +end_of_line = lf +# editorconfig-tools is unable to ignore longs strings or urls +max_line_length = off + +[CHANGELOG.md] +indent_size = false diff --git a/.github/workflows/node-pretest.yml b/.github/workflows/node-pretest.yml new file mode 100644 index 0000000000..48c68f5955 --- /dev/null +++ b/.github/workflows/node-pretest.yml @@ -0,0 +1,26 @@ +name: 'Tests: pretest/posttest' + +on: [pull_request, push] + +jobs: + pretest: + runs-on: ubuntu-latest + strategy: + fail-fast: false + matrix: + package: + - '..' + - eslint-config-airbnb + - eslint-config-airbnb-base + + defaults: + run: + working-directory: "packages/${{ matrix.package }}" + + steps: + - uses: actions/checkout@v2 + - uses: ljharb/actions/node/install@main + name: 'nvm install lts/* && npm install' + with: + node-version: 'lts/*' + - run: npm run pretest diff --git a/.github/workflows/node.yml b/.github/workflows/node.yml new file mode 100644 index 0000000000..6fc77ea08d --- /dev/null +++ b/.github/workflows/node.yml @@ -0,0 +1,163 @@ +name: 'Tests: node.js' + +on: [pull_request, push] + +jobs: + matrix: + runs-on: ubuntu-latest + outputs: + latest: ${{ steps.set-matrix.outputs.requireds }} + steps: + - uses: ljharb/actions/node/matrix@main + id: set-matrix + with: + versionsAsRoot: true + type: 'majors' + preset: '^12 || ^14 || ^16 || >= 17' + + base: + needs: [matrix] + name: 'base config' + runs-on: ubuntu-latest + + strategy: + fail-fast: false + matrix: + node-version: ${{ fromJson(needs.matrix.outputs.latest) }} + eslint: + - 8 + - 7 + package: + - eslint-config-airbnb-base + exclude: + - node-version: 10 + eslint: 8 + package: eslint-config-airbnb-base + + defaults: + run: + working-directory: "packages/${{ matrix.package }}" + + steps: + - uses: actions/checkout@v2 + - uses: ljharb/actions/node/install@main + name: 'nvm install ${{ matrix.node-version }} && npm install' + with: + before_install: cd "packages/${{ matrix.package }}" + node-version: ${{ matrix.node-version }} + after_install: | + npm install --no-save "eslint@${{ matrix.eslint }}" + - run: node -pe "require('eslint/package.json').version" + name: 'eslint version' + - run: npm run travis + - uses: codecov/codecov-action@v2 + + react: + needs: [matrix] + name: 'react config' + runs-on: ubuntu-latest + + strategy: + fail-fast: false + matrix: + node-version: ${{ fromJson(needs.matrix.outputs.latest) }} + eslint: + - 8 + - 7 + package: + - eslint-config-airbnb + react-hooks: + - 4 + + defaults: + run: + working-directory: "packages/${{ matrix.package }}" + + steps: + - uses: actions/checkout@v2 + - uses: ljharb/actions/node/install@main + name: 'nvm install ${{ matrix.node-version }} && npm install' + with: + before_install: cd "packages/${{ matrix.package }}" + node-version: ${{ matrix.node-version }} + after_install: | + npm install --no-save "eslint@${{ matrix.eslint }}" + - run: node -pe "require('eslint/package.json').version" + name: 'eslint version' + - run: npm install --no-save "eslint-plugin-react-hooks@${{ matrix.react-hooks }}" + if: ${{ matrix.react-hooks > 0}} + - run: npm run travis + - uses: codecov/codecov-action@v2 + + prepublish-base: + name: 'prepublish tests (base config)' + runs-on: ubuntu-latest + strategy: + fail-fast: false + matrix: + eslint: + - 8 + - 7 + package: + - eslint-config-airbnb-base + + defaults: + run: + working-directory: "packages/${{ matrix.package }}" + + steps: + - uses: actions/checkout@v2 + - uses: ljharb/actions/node/install@main + name: 'nvm install lts/* && npm install' + with: + before_install: cd "packages/${{ matrix.package }}" + node-version: lts/* + after_install: | + npm install --no-save "eslint@${{ matrix.eslint }}" + - run: node -pe "require('eslint/package.json').version" + name: 'eslint version' + - run: npm run pretravis + - run: npm run prepublishOnly + - run: npm run posttravis + + prepublish-react: + name: 'prepublish tests (react config)' + runs-on: ubuntu-latest + strategy: + fail-fast: false + matrix: + eslint: + - 8 + - 7 + package: + - eslint-config-airbnb + react-hooks: + - 4 + + defaults: + run: + working-directory: "packages/${{ matrix.package }}" + + steps: + - uses: actions/checkout@v2 + - uses: ljharb/actions/node/install@main + name: 'nvm install lts/* && npm install' + with: + before_install: cd "packages/${{ matrix.package }}" + node-version: lts/* + after_install: | + npm install --no-save "eslint@${{ matrix.eslint }}" + - run: npm install --no-save "eslint-plugin-react-hooks@${{ matrix.react-hooks }}" + if: ${{ matrix.react-hooks > 0}} + - run: node -pe "require('eslint/package.json').version" + name: 'eslint version' + - run: npm run pretravis + - run: npm run prepublishOnly + - run: npm run posttravis + + node: + name: 'node 10+' + needs: [base, prepublish-base, react, prepublish-react] + runs-on: ubuntu-latest + steps: + - run: 'echo tests completed' diff --git a/.github/workflows/rebase.yml b/.github/workflows/rebase.yml new file mode 100644 index 0000000000..027aed0797 --- /dev/null +++ b/.github/workflows/rebase.yml @@ -0,0 +1,15 @@ +name: Automatic Rebase + +on: [pull_request_target] + +jobs: + _: + name: "Automatic Rebase" + + runs-on: ubuntu-latest + + steps: + - uses: actions/checkout@v2 + - uses: ljharb/rebase@master + env: + GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }} diff --git a/.github/workflows/require-allow-edits.yml b/.github/workflows/require-allow-edits.yml new file mode 100644 index 0000000000..549d7b4823 --- /dev/null +++ b/.github/workflows/require-allow-edits.yml @@ -0,0 +1,12 @@ +name: Require “Allow Edits” + +on: [pull_request_target] + +jobs: + _: + name: "Require “Allow Edits”" + + runs-on: ubuntu-latest + + steps: + - uses: ljharb/require-allow-edits@main diff --git a/.gitignore b/.gitignore new file mode 100644 index 0000000000..ac10dfe528 --- /dev/null +++ b/.gitignore @@ -0,0 +1,7 @@ +# gitignore + +node_modules + +# Only apps should have lockfiles +yarn.lock +package-lock.json diff --git a/.npmrc b/.npmrc new file mode 100644 index 0000000000..43c97e719a --- /dev/null +++ b/.npmrc @@ -0,0 +1 @@ +package-lock=false diff --git a/LICENSE.md b/LICENSE.md new file mode 100644 index 0000000000..69d80c0252 --- /dev/null +++ b/LICENSE.md @@ -0,0 +1,21 @@ +MIT License + +Copyright (c) 2012 Airbnb + +Permission is hereby granted, free of charge, to any person obtaining a copy +of this software and associated documentation files (the "Software"), to deal +in the Software without restriction, including without limitation the rights +to use, copy, modify, merge, publish, distribute, sublicense, and/or sell +copies of the Software, and to permit persons to whom the Software is +furnished to do so, subject to the following conditions: + +The above copyright notice and this permission notice shall be included in all +copies or substantial portions of the Software. + +THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR +IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, +FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE +AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER +LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, +OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE +SOFTWARE. diff --git a/README.md b/README.md index 3a477b6c50..9a325a355b 100644 --- a/README.md +++ b/README.md @@ -2,650 +2,2437 @@ *A mostly reasonable approach to JavaScript* +> **Note**: this guide assumes you are using [Babel](https://babeljs.io), and requires that you use [babel-preset-airbnb](https://npmjs.com/babel-preset-airbnb) or the equivalent. It also assumes you are installing shims/polyfills in your app, with [airbnb-browser-shims](https://npmjs.com/airbnb-browser-shims) or the equivalent. -## Table of Contents +[![Downloads](https://img.shields.io/npm/dm/eslint-config-airbnb.svg)](https://www.npmjs.com/package/eslint-config-airbnb) +[![Downloads](https://img.shields.io/npm/dm/eslint-config-airbnb-base.svg)](https://www.npmjs.com/package/eslint-config-airbnb-base) +[![Gitter](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/airbnb/javascript?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge) + +This guide is available in other languages too. See [Translation](#translation) + +Other Style Guides + + - [ES5 (Deprecated)](https://github.com/airbnb/javascript/tree/es5-deprecated/es5) + - [React](react/) + - [CSS-in-JavaScript](css-in-javascript/) + - [CSS & Sass](https://github.com/airbnb/css) + - [Ruby](https://github.com/airbnb/ruby) + +## Table of Contents 1. [Types](#types) + 1. [References](#references) 1. [Objects](#objects) 1. [Arrays](#arrays) + 1. [Destructuring](#destructuring) 1. [Strings](#strings) 1. [Functions](#functions) + 1. [Arrow Functions](#arrow-functions) + 1. [Classes & Constructors](#classes--constructors) + 1. [Modules](#modules) + 1. [Iterators and Generators](#iterators-and-generators) 1. [Properties](#properties) 1. [Variables](#variables) 1. [Hoisting](#hoisting) - 1. [Conditional Expressions & Equality](#conditionals) + 1. [Comparison Operators & Equality](#comparison-operators--equality) 1. [Blocks](#blocks) + 1. [Control Statements](#control-statements) 1. [Comments](#comments) 1. [Whitespace](#whitespace) 1. [Commas](#commas) 1. [Semicolons](#semicolons) - 1. [Type Casting & Coercion](#type-coercion) + 1. [Type Casting & Coercion](#type-casting--coercion) 1. [Naming Conventions](#naming-conventions) 1. [Accessors](#accessors) - 1. [Constructors](#constructors) 1. [Events](#events) - 1. [Modules](#modules) 1. [jQuery](#jquery) - 1. [ES5 Compatibility](#es5) + 1. [ECMAScript 5 Compatibility](#ecmascript-5-compatibility) + 1. [ECMAScript 6+ (ES 2015+) Styles](#ecmascript-6-es-2015-styles) + 1. [Standard Library](#standard-library) 1. [Testing](#testing) 1. [Performance](#performance) 1. [Resources](#resources) 1. [In the Wild](#in-the-wild) 1. [Translation](#translation) - 1. [The JavaScript Style Guide Guide](#guide-guide) + 1. [The JavaScript Style Guide Guide](#the-javascript-style-guide-guide) + 1. [Chat With Us About JavaScript](#chat-with-us-about-javascript) 1. [Contributors](#contributors) 1. [License](#license) + 1. [Amendments](#amendments) -## Types +## Types - - **Primitives**: When you access a primitive type you work directly on its value + + - [1.1](#types--primitives) **Primitives**: When you access a primitive type you work directly on its value. - + `string` - + `number` - + `boolean` - + `null` - + `undefined` + - `string` + - `number` + - `boolean` + - `null` + - `undefined` + - `symbol` + - `bigint` + +
```javascript - var foo = 1, - bar = foo; + const foo = 1; + let bar = foo; bar = 9; console.log(foo, bar); // => 1, 9 ``` - - **Complex**: When you access a complex type you work on a reference to its value - + `object` - + `array` - + `function` + - Symbols and BigInts cannot be faithfully polyfilled, so they should not be used when targeting browsers/environments that don’t support them natively. + + + - [1.2](#types--complex) **Complex**: When you access a complex type you work on a reference to its value. + + - `object` + - `array` + - `function` + +
```javascript - var foo = [1, 2], - bar = foo; + const foo = [1, 2]; + const bar = foo; bar[0] = 9; console.log(foo[0], bar[0]); // => 9, 9 ``` - **[[⬆]](#TOC)** +**[⬆ back to top](#table-of-contents)** -## Objects +## References - - Use the literal syntax for object creation. + + - [2.1](#references--prefer-const) Use `const` for all of your references; avoid using `var`. eslint: [`prefer-const`](https://eslint.org/docs/rules/prefer-const), [`no-const-assign`](https://eslint.org/docs/rules/no-const-assign) + + > Why? This ensures that you can’t reassign your references, which can lead to bugs and difficult to comprehend code. ```javascript // bad - var item = new Object(); + var a = 1; + var b = 2; // good - var item = {}; + const a = 1; + const b = 2; ``` - - Don't use [reserved words](http://es5.github.io/#x7.6.1) as keys. It won't work in IE8. [More info](https://github.com/airbnb/javascript/issues/61) + + - [2.2](#references--disallow-var) If you must reassign references, use `let` instead of `var`. eslint: [`no-var`](https://eslint.org/docs/rules/no-var) + + > Why? `let` is block-scoped rather than function-scoped like `var`. ```javascript // bad - var superman = { - default: { clark: 'kent' }, - private: true - }; + var count = 1; + if (true) { + count += 1; + } - // good - var superman = { - defaults: { clark: 'kent' }, - hidden: true - }; + // good, use the let. + let count = 1; + if (true) { + count += 1; + } ``` - - Use readable synonyms in place of reserved words. + + - [2.3](#references--block-scope) Note that both `let` and `const` are block-scoped, whereas `var` is function-scoped. ```javascript - // bad - var superman = { - class: 'alien' - }; + // const and let only exist in the blocks they are defined in. + { + let a = 1; + const b = 1; + var c = 1; + } + console.log(a); // ReferenceError + console.log(b); // ReferenceError + console.log(c); // Prints 1 + ``` - // bad - var superman = { - klass: 'alien' - }; + In the above code, you can see that referencing `a` and `b` will produce a ReferenceError, while `c` contains the number. This is because `a` and `b` are block scoped, while `c` is scoped to the containing function. - // good - var superman = { - type: 'alien' - }; - ``` - **[[⬆]](#TOC)** +**[⬆ back to top](#table-of-contents)** -## Arrays +## Objects - - Use the literal syntax for array creation + + - [3.1](#objects--no-new) Use the literal syntax for object creation. eslint: [`no-new-object`](https://eslint.org/docs/rules/no-new-object) ```javascript // bad - var items = new Array(); + const item = new Object(); // good - var items = []; + const item = {}; ``` - - If you don't know array length use Array#push. + + - [3.2](#es6-computed-properties) Use computed property names when creating objects with dynamic property names. + + > Why? They allow you to define all the properties of an object in one place. ```javascript - var someStack = []; + function getKey(k) { + return `a key named ${k}`; + } // bad - someStack[someStack.length] = 'abracadabra'; + const obj = { + id: 5, + name: 'San Francisco', + }; + obj[getKey('enabled')] = true; // good - someStack.push('abracadabra'); + const obj = { + id: 5, + name: 'San Francisco', + [getKey('enabled')]: true, + }; ``` - - When you need to copy an array use Array#slice. [jsPerf](http://jsperf.com/converting-arguments-to-an-array/7) + + - [3.3](#es6-object-shorthand) Use object method shorthand. eslint: [`object-shorthand`](https://eslint.org/docs/rules/object-shorthand) ```javascript - var len = items.length, - itemsCopy = [], - i; - // bad - for (i = 0; i < len; i++) { - itemsCopy[i] = items[i]; - } + const atom = { + value: 1, - // good - itemsCopy = items.slice(); - ``` + addValue: function (value) { + return atom.value + value; + }, + }; - - To convert an array-like object to an array, use Array#slice. + // good + const atom = { + value: 1, - ```javascript - function trigger() { - var args = Array.prototype.slice.call(arguments); - ... - } + addValue(value) { + return atom.value + value; + }, + }; ``` - **[[⬆]](#TOC)** + + - [3.4](#es6-object-concise) Use property value shorthand. eslint: [`object-shorthand`](https://eslint.org/docs/rules/object-shorthand) - -## Strings - - - Use single quotes `''` for strings + > Why? It is shorter and descriptive. ```javascript - // bad - var name = "Bob Parr"; - - // good - var name = 'Bob Parr'; + const lukeSkywalker = 'Luke Skywalker'; // bad - var fullName = "Bob " + this.lastName; + const obj = { + lukeSkywalker: lukeSkywalker, + }; // good - var fullName = 'Bob ' + this.lastName; + const obj = { + lukeSkywalker, + }; ``` - - Strings longer than 80 characters should be written across multiple lines using string concatenation. - - Note: If overused, long strings with concatenation could impact performance. [jsPerf](http://jsperf.com/ya-string-concat) & [Discussion](https://github.com/airbnb/javascript/issues/40) + + - [3.5](#objects--grouped-shorthand) Group your shorthand properties at the beginning of your object declaration. + + > Why? It’s easier to tell which properties are using the shorthand. ```javascript - // bad - var errorMessage = 'This is a super long error that was thrown because of Batman. When you stop to think about how Batman had anything to do with this, you would get nowhere fast.'; + const anakinSkywalker = 'Anakin Skywalker'; + const lukeSkywalker = 'Luke Skywalker'; // bad - var errorMessage = 'This is a super long error that \ - was thrown because of Batman. \ - When you stop to think about \ - how Batman had anything to do \ - with this, you would get nowhere \ - fast.'; - + const obj = { + episodeOne: 1, + twoJediWalkIntoACantina: 2, + lukeSkywalker, + episodeThree: 3, + mayTheFourth: 4, + anakinSkywalker, + }; // good - var errorMessage = 'This is a super long error that ' + - 'was thrown because of Batman. ' + - 'When you stop to think about ' + - 'how Batman had anything to do ' + - 'with this, you would get nowhere ' + - 'fast.'; + const obj = { + lukeSkywalker, + anakinSkywalker, + episodeOne: 1, + twoJediWalkIntoACantina: 2, + episodeThree: 3, + mayTheFourth: 4, + }; ``` - - When programatically building up a string, use Array#join instead of string concatenation. Mostly for IE: [jsPerf](http://jsperf.com/string-vs-array-concat/2). - - ```javascript - var items, - messages, - length, - i; - - messages = [{ - state: 'success', - message: 'This one worked.' - }, { - state: 'success', - message: 'This one worked as well.' - }, { - state: 'error', - message: 'This one did not work.' - }]; + + - [3.6](#objects--quoted-props) Only quote properties that are invalid identifiers. eslint: [`quote-props`](https://eslint.org/docs/rules/quote-props) - length = messages.length; + > Why? In general we consider it subjectively easier to read. It improves syntax highlighting, and is also more easily optimized by many JS engines. + ```javascript // bad - function inbox(messages) { - items = ''; - } + const bad = { + 'foo': 3, + 'bar': 4, + 'data-blah': 5, + }; // good - function inbox(messages) { - items = []; - - for (i = 0; i < length; i++) { - items[i] = messages[i].message; - } - - return ''; - } + const good = { + foo: 3, + bar: 4, + 'data-blah': 5, + }; ``` - **[[⬆]](#TOC)** + + - [3.7](#objects--prototype-builtins) Do not call `Object.prototype` methods directly, such as `hasOwnProperty`, `propertyIsEnumerable`, and `isPrototypeOf`. eslint: [`no-prototype-builtins`](https://eslint.org/docs/rules/no-prototype-builtins) + > Why? These methods may be shadowed by properties on the object in question - consider `{ hasOwnProperty: false }` - or, the object may be a null object (`Object.create(null)`). In modern browsers that support ES2022, or with a polyfill such as , `Object.hasOwn` can also be used as an alternative to `Object.prototype.hasOwnProperty.call`. -## Functions + ```javascript + // bad + console.log(object.hasOwnProperty(key)); - - Function expressions: + // good + console.log(Object.prototype.hasOwnProperty.call(object, key)); - ```javascript - // anonymous function expression - var anonymous = function() { - return true; - }; + // better + const has = Object.prototype.hasOwnProperty; // cache the lookup once, in module scope. + console.log(has.call(object, key)); - // named function expression - var named = function named() { - return true; - }; + // best + console.log(Object.hasOwn(object, key)); // only supported in browsers that support ES2022 - // immediately-invoked function expression (IIFE) - (function() { - console.log('Welcome to the Internet. Please follow me.'); - })(); + /* or */ + import has from 'has'; // https://www.npmjs.com/package/has + console.log(has(object, key)); + /* or */ + console.log(Object.hasOwn(object, key)); // https://www.npmjs.com/package/object.hasown ``` - - Never declare a function in a non-function block (if, while, etc). Assign the function to a variable instead. Browsers will allow you to do it, but they all interpret it differently, which is bad news bears. - - **Note:** ECMA-262 defines a `block` as a list of statements. A function declaration is not a statement. [Read ECMA-262's note on this issue](http://www.ecma-international.org/publications/files/ECMA-ST/Ecma-262.pdf#page=97). + + - [3.8](#objects--rest-spread) Prefer the object spread syntax over [`Object.assign`](https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Object/assign) to shallow-copy objects. Use the object rest parameter syntax to get a new object with certain properties omitted. eslint: [`prefer-object-spread`](https://eslint.org/docs/rules/prefer-object-spread) ```javascript + // very bad + const original = { a: 1, b: 2 }; + const copy = Object.assign(original, { c: 3 }); // this mutates `original` ಠ_ಠ + delete copy.a; // so does this + // bad - if (currentUser) { - function test() { - console.log('Nope.'); - } - } + const original = { a: 1, b: 2 }; + const copy = Object.assign({}, original, { c: 3 }); // copy => { a: 1, b: 2, c: 3 } // good - var test; - if (currentUser) { - test = function test() { - console.log('Yup.'); - }; - } + const original = { a: 1, b: 2 }; + const copy = { ...original, c: 3 }; // copy => { a: 1, b: 2, c: 3 } + + const { a, ...noA } = copy; // noA => { b: 2, c: 3 } ``` - - Never name a parameter `arguments`, this will take precedence over the `arguments` object that is given to every function scope. +**[⬆ back to top](#table-of-contents)** + +## Arrays + + + - [4.1](#arrays--literals) Use the literal syntax for array creation. eslint: [`no-array-constructor`](https://eslint.org/docs/rules/no-array-constructor) ```javascript // bad - function nope(name, options, arguments) { - // ...stuff... - } + const items = new Array(); // good - function yup(name, options, args) { - // ...stuff... - } + const items = []; ``` - **[[⬆]](#TOC)** - - - -## Properties - - - Use dot notation when accessing properties. + + - [4.2](#arrays--push) Use [Array#push](https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Array/push) instead of direct assignment to add items to an array. ```javascript - var luke = { - jedi: true, - age: 28 - }; + const someStack = []; // bad - var isJedi = luke['jedi']; + someStack[someStack.length] = 'abracadabra'; // good - var isJedi = luke.jedi; + someStack.push('abracadabra'); ``` - - Use subscript notation `[]` when accessing properties with a variable. + + - [4.3](#es6-array-spreads) Use array spreads `...` to copy arrays. ```javascript - var luke = { - jedi: true, - age: 28 - }; + // bad + const len = items.length; + const itemsCopy = []; + let i; - function getProp(prop) { - return luke[prop]; + for (i = 0; i < len; i += 1) { + itemsCopy[i] = items[i]; } - var isJedi = getProp('jedi'); + // good + const itemsCopy = [...items]; ``` - **[[⬆]](#TOC)** - - -## Variables - - - Always use `var` to declare variables. Not doing so will result in global variables. We want to avoid polluting the global namespace. Captain Planet warned us of that. + + + - [4.4](#arrays--from-iterable) To convert an iterable object to an array, use spreads `...` instead of [`Array.from`](https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Array/from) ```javascript - // bad - superPower = new SuperPower(); + const foo = document.querySelectorAll('.foo'); // good - var superPower = new SuperPower(); + const nodes = Array.from(foo); + + // best + const nodes = [...foo]; ``` - - Use one `var` declaration for multiple variables and declare each variable on a newline. + + - [4.5](#arrays--from-array-like) Use [`Array.from`](https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Array/from) for converting an array-like object to an array. ```javascript + const arrLike = { 0: 'foo', 1: 'bar', 2: 'baz', length: 3 }; + // bad - var items = getItems(); - var goSportsTeam = true; - var dragonball = 'z'; + const arr = Array.prototype.slice.call(arrLike); // good - var items = getItems(), - goSportsTeam = true, - dragonball = 'z'; + const arr = Array.from(arrLike); ``` - - Declare unassigned variables last. This is helpful when later on you might need to assign a variable depending on one of the previous assigned variables. + + - [4.6](#arrays--mapping) Use [`Array.from`](https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Array/from) instead of spread `...` for mapping over iterables, because it avoids creating an intermediate array. ```javascript // bad - var i, len, dragonball, - items = getItems(), - goSportsTeam = true; - - // bad - var i, items = getItems(), - dragonball, - goSportsTeam = true, - len; + const baz = [...foo].map(bar); // good - var items = getItems(), - goSportsTeam = true, - dragonball, - length, - i; + const baz = Array.from(foo, bar); ``` - - Assign variables at the top of their scope. This helps avoid issues with variable declaration and assignment hoisting related issues. + + - [4.7](#arrays--callback-return) Use return statements in array method callbacks. It’s ok to omit the return if the function body consists of a single statement returning an expression without side effects, following [8.2](#arrows--implicit-return). eslint: [`array-callback-return`](https://eslint.org/docs/rules/array-callback-return) ```javascript - // bad - function() { - test(); - console.log('doing stuff..'); + // good + [1, 2, 3].map((x) => { + const y = x + 1; + return x * y; + }); - //..other stuff.. + // good + [1, 2, 3].map((x) => x + 1); - var name = getName(); + // bad - no returned value means `acc` becomes undefined after the first iteration + [[0, 1], [2, 3], [4, 5]].reduce((acc, item, index) => { + const flatten = acc.concat(item); + }); - if (name === 'test') { + // good + [[0, 1], [2, 3], [4, 5]].reduce((acc, item, index) => { + const flatten = acc.concat(item); + return flatten; + }); + + // bad + inbox.filter((msg) => { + const { subject, author } = msg; + if (subject === 'Mockingbird') { + return author === 'Harper Lee'; + } else { return false; } - - return name; - } + }); // good - function() { - var name = getName(); - - test(); - console.log('doing stuff..'); - - //..other stuff.. - - if (name === 'test') { - return false; + inbox.filter((msg) => { + const { subject, author } = msg; + if (subject === 'Mockingbird') { + return author === 'Harper Lee'; } - return name; - } + return false; + }); + ``` + + - [4.8](#arrays--bracket-newline) Use line breaks after opening array brackets and before closing array brackets, if an array has multiple lines + + ```javascript // bad - function() { - var name = getName(); + const arr = [ + [0, 1], [2, 3], [4, 5], + ]; - if (!arguments.length) { - return false; - } + const objectInArray = [{ + id: 1, + }, { + id: 2, + }]; - return true; - } + const numberInArray = [ + 1, 2, + ]; // good - function() { - if (!arguments.length) { - return false; - } + const arr = [[0, 1], [2, 3], [4, 5]]; - var name = getName(); + const objectInArray = [ + { + id: 1, + }, + { + id: 2, + }, + ]; - return true; - } + const numberInArray = [ + 1, + 2, + ]; ``` - **[[⬆]](#TOC)** +**[⬆ back to top](#table-of-contents)** +## Destructuring -## Hoisting + + - [5.1](#destructuring--object) Use object destructuring when accessing and using multiple properties of an object. eslint: [`prefer-destructuring`](https://eslint.org/docs/rules/prefer-destructuring) - - Variable declarations get hoisted to the top of their scope, their assignment does not. + > Why? Destructuring saves you from creating temporary references for those properties, and from repetitive access of the object. Repeating object access creates more repetitive code, requires more reading, and creates more opportunities for mistakes. Destructuring objects also provides a single site of definition of the object structure that is used in the block, rather than requiring reading the entire block to determine what is used. ```javascript - // we know this wouldn't work (assuming there - // is no notDefined global variable) - function example() { - console.log(notDefined); // => throws a ReferenceError + // bad + function getFullName(user) { + const firstName = user.firstName; + const lastName = user.lastName; + + return `${firstName} ${lastName}`; } - // creating a variable declaration after you - // reference the variable will work due to - // variable hoisting. Note: the assignment - // value of `true` is not hoisted. - function example() { - console.log(declaredButNotAssigned); // => undefined - var declaredButNotAssigned = true; + // good + function getFullName(user) { + const { firstName, lastName } = user; + return `${firstName} ${lastName}`; } - // The interpreter is hoisting the variable - // declaration to the top of the scope. - // Which means our example could be rewritten as: - function example() { - var declaredButNotAssigned; - console.log(declaredButNotAssigned); // => undefined - declaredButNotAssigned = true; + // best + function getFullName({ firstName, lastName }) { + return `${firstName} ${lastName}`; } ``` - - Anonymous function expressions hoist their variable name, but not the function assignment. + + - [5.2](#destructuring--array) Use array destructuring. eslint: [`prefer-destructuring`](https://eslint.org/docs/rules/prefer-destructuring) ```javascript - function example() { - console.log(anonymous); // => undefined + const arr = [1, 2, 3, 4]; - anonymous(); // => TypeError anonymous is not a function + // bad + const first = arr[0]; + const second = arr[1]; - var anonymous = function() { - console.log('anonymous function expression'); - }; - } + // good + const [first, second] = arr; ``` - - Named function expressions hoist the variable name, not the function name or the function body. + + - [5.3](#destructuring--object-over-array) Use object destructuring for multiple return values, not array destructuring. - ```javascript - function example() { - console.log(named); // => undefined + > Why? You can add new properties over time or change the order of things without breaking call sites. - named(); // => TypeError named is not a function + ```javascript + // bad + function processInput(input) { + // then a miracle occurs + return [left, right, top, bottom]; + } - superPower(); // => ReferenceError superPower is not defined + // the caller needs to think about the order of return data + const [left, __, top] = processInput(input); - var named = function superPower() { - console.log('Flying'); - }; + // good + function processInput(input) { + // then a miracle occurs + return { left, right, top, bottom }; } - // the same is true when the function name - // is the same as the variable name. - function example() { - console.log(named); // => undefined + // the caller selects only the data they need + const { left, top } = processInput(input); + ``` - named(); // => TypeError named is not a function +**[⬆ back to top](#table-of-contents)** - var named = function named() { - console.log('named'); - } - } - ``` +## Strings - - Function declarations hoist their name and the function body. + + - [6.1](#strings--quotes) Use single quotes `''` for strings. eslint: [`quotes`](https://eslint.org/docs/rules/quotes) ```javascript - function example() { - superPower(); // => Flying + // bad + const name = "Capt. Janeway"; - function superPower() { - console.log('Flying'); - } - } + // bad - template literals should contain interpolation or newlines + const name = `Capt. Janeway`; + + // good + const name = 'Capt. Janeway'; ``` - - For more information refer to [JavaScript Scoping & Hoisting](http://www.adequatelygood.com/2010/2/JavaScript-Scoping-and-Hoisting) by [Ben Cherry](http://www.adequatelygood.com/) + + - [6.2](#strings--line-length) Strings that cause the line to go over 100 characters should not be written across multiple lines using string concatenation. - **[[⬆]](#TOC)** + > Why? Broken strings are painful to work with and make code less searchable. + ```javascript + // bad + const errorMessage = 'This is a super long error that was thrown because \ + of Batman. When you stop to think about how Batman had anything to do \ + with this, you would get nowhere \ + fast.'; + // bad + const errorMessage = 'This is a super long error that was thrown because ' + + 'of Batman. When you stop to think about how Batman had anything to do ' + + 'with this, you would get nowhere fast.'; -## Conditional Expressions & Equality + // good + const errorMessage = 'This is a super long error that was thrown because of Batman. When you stop to think about how Batman had anything to do with this, you would get nowhere fast.'; + ``` - - Use `===` and `!==` over `==` and `!=`. - - Conditional expressions are evaluated using coercion with the `ToBoolean` method and always follow these simple rules: + + - [6.3](#es6-template-literals) When programmatically building up strings, use template strings instead of concatenation. eslint: [`prefer-template`](https://eslint.org/docs/rules/prefer-template) [`template-curly-spacing`](https://eslint.org/docs/rules/template-curly-spacing) - + **Objects** evaluate to **true** - + **Undefined** evaluates to **false** - + **Null** evaluates to **false** - + **Booleans** evaluate to **the value of the boolean** - + **Numbers** evaluate to **false** if **+0, -0, or NaN**, otherwise **true** - + **Strings** evaluate to **false** if an empty string `''`, otherwise **true** + > Why? Template strings give you a readable, concise syntax with proper newlines and string interpolation features. ```javascript - if ([0]) { - // true - // An array is an object, objects evaluate to true + // bad + function sayHi(name) { + return 'How are you, ' + name + '?'; } - ``` - - Use shortcuts. + // bad + function sayHi(name) { + return ['How are you, ', name, '?'].join(); + } - ```javascript // bad - if (name !== '') { - // ...stuff... + function sayHi(name) { + return `How are you, ${ name }?`; } // good - if (name) { - // ...stuff... + function sayHi(name) { + return `How are you, ${name}?`; } + ``` + + - [6.4](#strings--eval) Never use `eval()` on a string; it opens too many vulnerabilities. eslint: [`no-eval`](https://eslint.org/docs/rules/no-eval) + + + - [6.5](#strings--escaping) Do not unnecessarily escape characters in strings. eslint: [`no-useless-escape`](https://eslint.org/docs/rules/no-useless-escape) + + > Why? Backslashes harm readability, thus they should only be present when necessary. + + ```javascript // bad - if (collection.length > 0) { - // ...stuff... - } + const foo = '\'this\' \i\s \"quoted\"'; // good - if (collection.length) { - // ...stuff... - } + const foo = '\'this\' is "quoted"'; + const foo = `my name is '${name}'`; ``` - - For more information see [Truth Equality and JavaScript](http://javascriptweblog.wordpress.com/2011/02/07/truth-equality-and-javascript/#more-2108) by Angus Croll +**[⬆ back to top](#table-of-contents)** - **[[⬆]](#TOC)** +## Functions + + - [7.1](#functions--declarations) Use named function expressions instead of function declarations. eslint: [`func-style`](https://eslint.org/docs/rules/func-style), [`func-names`](https://eslint.org/docs/latest/rules/func-names) -## Blocks - - - Use braces with all multi-line blocks. + > Why? Function declarations are hoisted, which means that it’s easy - too easy - to reference the function before it is defined in the file. This harms readability and maintainability. If you find that a function’s definition is large or complex enough that it is interfering with understanding the rest of the file, then perhaps it’s time to extract it to its own module! Don’t forget to explicitly name the expression, regardless of whether or not the name is inferred from the containing variable (which is often the case in modern browsers or when using compilers such as Babel). This eliminates any assumptions made about the Error’s call stack. ([Discussion](https://github.com/airbnb/javascript/issues/794)) ```javascript // bad - if (test) - return false; + function foo() { + // ... + } + + // bad + const foo = function () { + // ... + }; + + // good + // lexical name distinguished from the variable-referenced invocation(s) + const short = function longUniqueMoreDescriptiveLexicalFoo() { + // ... + }; + ``` + + + - [7.2](#functions--iife) Wrap immediately invoked function expressions in parentheses. eslint: [`wrap-iife`](https://eslint.org/docs/rules/wrap-iife) + + > Why? An immediately invoked function expression is a single unit - wrapping both it, and its invocation parens, in parens, cleanly expresses this. Note that in a world with modules everywhere, you almost never need an IIFE. + + ```javascript + // immediately-invoked function expression (IIFE) + (function () { + console.log('Welcome to the Internet. Please follow me.'); + }()); + ``` + + + - [7.3](#functions--in-blocks) Never declare a function in a non-function block (`if`, `while`, etc). Assign the function to a variable instead. Browsers will allow you to do it, but they all interpret it differently, which is bad news bears. eslint: [`no-loop-func`](https://eslint.org/docs/rules/no-loop-func) + + + - [7.4](#functions--note-on-blocks) **Note:** ECMA-262 defines a `block` as a list of statements. A function declaration is not a statement. + + ```javascript + // bad + if (currentUser) { + function test() { + console.log('Nope.'); + } + } + + // good + let test; + if (currentUser) { + test = () => { + console.log('Yup.'); + }; + } + ``` + + + - [7.5](#functions--arguments-shadow) Never name a parameter `arguments`. This will take precedence over the `arguments` object that is given to every function scope. + + ```javascript + // bad + function foo(name, options, arguments) { + // ... + } + + // good + function foo(name, options, args) { + // ... + } + ``` + + + - [7.6](#es6-rest) Never use `arguments`, opt to use rest syntax `...` instead. eslint: [`prefer-rest-params`](https://eslint.org/docs/rules/prefer-rest-params) + + > Why? `...` is explicit about which arguments you want pulled. Plus, rest arguments are a real Array, and not merely Array-like like `arguments`. + + ```javascript + // bad + function concatenateAll() { + const args = Array.prototype.slice.call(arguments); + return args.join(''); + } + + // good + function concatenateAll(...args) { + return args.join(''); + } + ``` + + + - [7.7](#es6-default-parameters) Use default parameter syntax rather than mutating function arguments. + + ```javascript + // really bad + function handleThings(opts) { + // No! We shouldn’t mutate function arguments. + // Double bad: if opts is falsy it'll be set to an object which may + // be what you want but it can introduce subtle bugs. + opts = opts || {}; + // ... + } + + // still bad + function handleThings(opts) { + if (opts === void 0) { + opts = {}; + } + // ... + } + + // good + function handleThings(opts = {}) { + // ... + } + ``` + + + - [7.8](#functions--default-side-effects) Avoid side effects with default parameters. + + > Why? They are confusing to reason about. + + ```javascript + let b = 1; + // bad + function count(a = b++) { + console.log(a); + } + count(); // 1 + count(); // 2 + count(3); // 3 + count(); // 3 + ``` + + + - [7.9](#functions--defaults-last) Always put default parameters last. eslint: [`default-param-last`](https://eslint.org/docs/rules/default-param-last) + + ```javascript + // bad + function handleThings(opts = {}, name) { + // ... + } + + // good + function handleThings(name, opts = {}) { + // ... + } + ``` + + + - [7.10](#functions--constructor) Never use the Function constructor to create a new function. eslint: [`no-new-func`](https://eslint.org/docs/rules/no-new-func) + + > Why? Creating a function in this way evaluates a string similarly to `eval()`, which opens vulnerabilities. + + ```javascript + // bad + const add = new Function('a', 'b', 'return a + b'); + + // still bad + const subtract = Function('a', 'b', 'return a - b'); + ``` + + + - [7.11](#functions--signature-spacing) Spacing in a function signature. eslint: [`space-before-function-paren`](https://eslint.org/docs/rules/space-before-function-paren) [`space-before-blocks`](https://eslint.org/docs/rules/space-before-blocks) + + > Why? Consistency is good, and you shouldn’t have to add or remove a space when adding or removing a name. + + ```javascript + // bad + const f = function(){}; + const g = function (){}; + const h = function() {}; + + // good + const x = function () {}; + const y = function a() {}; + ``` + + + - [7.12](#functions--mutate-params) Never mutate parameters. eslint: [`no-param-reassign`](https://eslint.org/docs/rules/no-param-reassign) + + > Why? Manipulating objects passed in as parameters can cause unwanted variable side effects in the original caller. + + ```javascript + // bad + function f1(obj) { + obj.key = 1; + } + + // good + function f2(obj) { + const key = Object.prototype.hasOwnProperty.call(obj, 'key') ? obj.key : 1; + } + ``` + + + - [7.13](#functions--reassign-params) Never reassign parameters. eslint: [`no-param-reassign`](https://eslint.org/docs/rules/no-param-reassign) + + > Why? Reassigning parameters can lead to unexpected behavior, especially when accessing the `arguments` object. It can also cause optimization issues, especially in V8. + + ```javascript + // bad + function f1(a) { + a = 1; + // ... + } + + function f2(a) { + if (!a) { a = 1; } + // ... + } + + // good + function f3(a) { + const b = a || 1; + // ... + } + + function f4(a = 1) { + // ... + } + ``` + + + - [7.14](#functions--spread-vs-apply) Prefer the use of the spread syntax `...` to call variadic functions. eslint: [`prefer-spread`](https://eslint.org/docs/rules/prefer-spread) + + > Why? It’s cleaner, you don’t need to supply a context, and you can not easily compose `new` with `apply`. + + ```javascript + // bad + const x = [1, 2, 3, 4, 5]; + console.log.apply(console, x); + + // good + const x = [1, 2, 3, 4, 5]; + console.log(...x); + + // bad + new (Function.prototype.bind.apply(Date, [null, 2016, 8, 5])); + + // good + new Date(...[2016, 8, 5]); + ``` + + + - [7.15](#functions--signature-invocation-indentation) Functions with multiline signatures, or invocations, should be indented just like every other multiline list in this guide: with each item on a line by itself, with a trailing comma on the last item. eslint: [`function-paren-newline`](https://eslint.org/docs/rules/function-paren-newline) + + ```javascript + // bad + function foo(bar, + baz, + quux) { + // ... + } + + // good + function foo( + bar, + baz, + quux, + ) { + // ... + } + + // bad + console.log(foo, + bar, + baz); + + // good + console.log( + foo, + bar, + baz, + ); + ``` + +**[⬆ back to top](#table-of-contents)** + +## Arrow Functions + + + - [8.1](#arrows--use-them) When you must use an anonymous function (as when passing an inline callback), use arrow function notation. eslint: [`prefer-arrow-callback`](https://eslint.org/docs/rules/prefer-arrow-callback), [`arrow-spacing`](https://eslint.org/docs/rules/arrow-spacing) + + > Why? It creates a version of the function that executes in the context of `this`, which is usually what you want, and is a more concise syntax. + + > Why not? If you have a fairly complicated function, you might move that logic out into its own named function expression. + + ```javascript + // bad + [1, 2, 3].map(function (x) { + const y = x + 1; + return x * y; + }); + + // good + [1, 2, 3].map((x) => { + const y = x + 1; + return x * y; + }); + ``` + + + - [8.2](#arrows--implicit-return) If the function body consists of a single statement returning an [expression](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Expressions_and_Operators#Expressions) without side effects, omit the braces and use the implicit return. Otherwise, keep the braces and use a `return` statement. eslint: [`arrow-parens`](https://eslint.org/docs/rules/arrow-parens), [`arrow-body-style`](https://eslint.org/docs/rules/arrow-body-style) + + > Why? Syntactic sugar. It reads well when multiple functions are chained together. + + ```javascript + // bad + [1, 2, 3].map((number) => { + const nextNumber = number + 1; + `A string containing the ${nextNumber}.`; + }); + + // good + [1, 2, 3].map((number) => `A string containing the ${number + 1}.`); + + // good + [1, 2, 3].map((number) => { + const nextNumber = number + 1; + return `A string containing the ${nextNumber}.`; + }); + + // good + [1, 2, 3].map((number, index) => ({ + [index]: number, + })); + + // No implicit return with side effects + function foo(callback) { + const val = callback(); + if (val === true) { + // Do something if callback returns true + } + } + + let bool = false; + + // bad + foo(() => bool = true); + + // good + foo(() => { + bool = true; + }); + ``` + + + - [8.3](#arrows--paren-wrap) In case the expression spans over multiple lines, wrap it in parentheses for better readability. + + > Why? It shows clearly where the function starts and ends. + + ```javascript + // bad + ['get', 'post', 'put'].map((httpMethod) => Object.prototype.hasOwnProperty.call( + httpMagicObjectWithAVeryLongName, + httpMethod, + ) + ); + + // good + ['get', 'post', 'put'].map((httpMethod) => ( + Object.prototype.hasOwnProperty.call( + httpMagicObjectWithAVeryLongName, + httpMethod, + ) + )); + ``` + + + - [8.4](#arrows--one-arg-parens) Always include parentheses around arguments for clarity and consistency. eslint: [`arrow-parens`](https://eslint.org/docs/rules/arrow-parens) + + > Why? Minimizes diff churn when adding or removing arguments. + + ```javascript + // bad + [1, 2, 3].map(x => x * x); + + // good + [1, 2, 3].map((x) => x * x); + + // bad + [1, 2, 3].map(number => ( + `A long string with the ${number}. It’s so long that we don’t want it to take up space on the .map line!` + )); + + // good + [1, 2, 3].map((number) => ( + `A long string with the ${number}. It’s so long that we don’t want it to take up space on the .map line!` + )); + + // bad + [1, 2, 3].map(x => { + const y = x + 1; + return x * y; + }); + + // good + [1, 2, 3].map((x) => { + const y = x + 1; + return x * y; + }); + ``` + + + - [8.5](#arrows--confusing) Avoid confusing arrow function syntax (`=>`) with comparison operators (`<=`, `>=`). eslint: [`no-confusing-arrow`](https://eslint.org/docs/rules/no-confusing-arrow) + + ```javascript + // bad + const itemHeight = (item) => item.height <= 256 ? item.largeSize : item.smallSize; + + // bad + const itemHeight = (item) => item.height >= 256 ? item.largeSize : item.smallSize; + + // good + const itemHeight = (item) => (item.height <= 256 ? item.largeSize : item.smallSize); + + // good + const itemHeight = (item) => { + const { height, largeSize, smallSize } = item; + return height <= 256 ? largeSize : smallSize; + }; + ``` + + + - [8.6](#whitespace--implicit-arrow-linebreak) Enforce the location of arrow function bodies with implicit returns. eslint: [`implicit-arrow-linebreak`](https://eslint.org/docs/rules/implicit-arrow-linebreak) + + ```javascript + // bad + (foo) => + bar; + + (foo) => + (bar); + + // good + (foo) => bar; + (foo) => (bar); + (foo) => ( + bar + ) + ``` + +**[⬆ back to top](#table-of-contents)** + +## Classes & Constructors + + + - [9.1](#constructors--use-class) Always use `class`. Avoid manipulating `prototype` directly. + + > Why? `class` syntax is more concise and easier to reason about. + + ```javascript + // bad + function Queue(contents = []) { + this.queue = [...contents]; + } + Queue.prototype.pop = function () { + const value = this.queue[0]; + this.queue.splice(0, 1); + return value; + }; + + // good + class Queue { + constructor(contents = []) { + this.queue = [...contents]; + } + pop() { + const value = this.queue[0]; + this.queue.splice(0, 1); + return value; + } + } + ``` + + + - [9.2](#constructors--extends) Use `extends` for inheritance. + + > Why? It is a built-in way to inherit prototype functionality without breaking `instanceof`. + + ```javascript + // bad + const inherits = require('inherits'); + function PeekableQueue(contents) { + Queue.apply(this, contents); + } + inherits(PeekableQueue, Queue); + PeekableQueue.prototype.peek = function () { + return this.queue[0]; + }; + + // good + class PeekableQueue extends Queue { + peek() { + return this.queue[0]; + } + } + ``` + + + - [9.3](#constructors--chaining) Methods can return `this` to help with method chaining. + + ```javascript + // bad + Jedi.prototype.jump = function () { + this.jumping = true; + return true; + }; + + Jedi.prototype.setHeight = function (height) { + this.height = height; + }; + + const luke = new Jedi(); + luke.jump(); // => true + luke.setHeight(20); // => undefined + + // good + class Jedi { + jump() { + this.jumping = true; + return this; + } + + setHeight(height) { + this.height = height; + return this; + } + } + + const luke = new Jedi(); + + luke.jump() + .setHeight(20); + ``` + + + - [9.4](#constructors--tostring) It’s okay to write a custom `toString()` method, just make sure it works successfully and causes no side effects. + + ```javascript + class Jedi { + constructor(options = {}) { + this.name = options.name || 'no name'; + } + + getName() { + return this.name; + } + + toString() { + return `Jedi - ${this.getName()}`; + } + } + ``` + + + - [9.5](#constructors--no-useless) Classes have a default constructor if one is not specified. An empty constructor function or one that just delegates to a parent class is unnecessary. eslint: [`no-useless-constructor`](https://eslint.org/docs/rules/no-useless-constructor) + + ```javascript + // bad + class Jedi { + constructor() {} + + getName() { + return this.name; + } + } + + // bad + class Rey extends Jedi { + constructor(...args) { + super(...args); + } + } + + // good + class Rey extends Jedi { + constructor(...args) { + super(...args); + this.name = 'Rey'; + } + } + ``` + + + - [9.6](#classes--no-duplicate-members) Avoid duplicate class members. eslint: [`no-dupe-class-members`](https://eslint.org/docs/rules/no-dupe-class-members) + + > Why? Duplicate class member declarations will silently prefer the last one - having duplicates is almost certainly a bug. + + ```javascript + // bad + class Foo { + bar() { return 1; } + bar() { return 2; } + } + + // good + class Foo { + bar() { return 1; } + } + + // good + class Foo { + bar() { return 2; } + } + ``` + + + - [9.7](#classes--methods-use-this) Class methods should use `this` or be made into a static method unless an external library or framework requires using specific non-static methods. Being an instance method should indicate that it behaves differently based on properties of the receiver. eslint: [`class-methods-use-this`](https://eslint.org/docs/rules/class-methods-use-this) + + ```javascript + // bad + class Foo { + bar() { + console.log('bar'); + } + } + + // good - this is used + class Foo { + bar() { + console.log(this.bar); + } + } + + // good - constructor is exempt + class Foo { + constructor() { + // ... + } + } + + // good - static methods aren't expected to use this + class Foo { + static bar() { + console.log('bar'); + } + } + ``` + +**[⬆ back to top](#table-of-contents)** + +## Modules + + + - [10.1](#modules--use-them) Always use modules (`import`/`export`) over a non-standard module system. You can always transpile to your preferred module system. + + > Why? Modules are the future, let’s start using the future now. + + ```javascript + // bad + const AirbnbStyleGuide = require('./AirbnbStyleGuide'); + module.exports = AirbnbStyleGuide.es6; + + // ok + import AirbnbStyleGuide from './AirbnbStyleGuide'; + export default AirbnbStyleGuide.es6; + + // best + import { es6 } from './AirbnbStyleGuide'; + export default es6; + ``` + + + - [10.2](#modules--no-wildcard) Do not use wildcard imports. + + > Why? This makes sure you have a single default export. + + ```javascript + // bad + import * as AirbnbStyleGuide from './AirbnbStyleGuide'; + + // good + import AirbnbStyleGuide from './AirbnbStyleGuide'; + ``` + + + - [10.3](#modules--no-export-from-import) And do not export directly from an import. + + > Why? Although the one-liner is concise, having one clear way to import and one clear way to export makes things consistent. + + ```javascript + // bad + // filename es6.js + export { es6 as default } from './AirbnbStyleGuide'; + + // good + // filename es6.js + import { es6 } from './AirbnbStyleGuide'; + export default es6; + ``` + + + - [10.4](#modules--no-duplicate-imports) Only import from a path in one place. + eslint: [`no-duplicate-imports`](https://eslint.org/docs/rules/no-duplicate-imports) + > Why? Having multiple lines that import from the same path can make code harder to maintain. + + ```javascript + // bad + import foo from 'foo'; + // … some other imports … // + import { named1, named2 } from 'foo'; + + // good + import foo, { named1, named2 } from 'foo'; + + // good + import foo, { + named1, + named2, + } from 'foo'; + ``` + + + - [10.5](#modules--no-mutable-exports) Do not export mutable bindings. + eslint: [`import/no-mutable-exports`](https://github.com/import-js/eslint-plugin-import/blob/master/docs/rules/no-mutable-exports.md) + > Why? Mutation should be avoided in general, but in particular when exporting mutable bindings. While this technique may be needed for some special cases, in general, only constant references should be exported. + + ```javascript + // bad + let foo = 3; + export { foo }; + + // good + const foo = 3; + export { foo }; + ``` + + + - [10.6](#modules--prefer-default-export) In modules with a single export, prefer default export over named export. + eslint: [`import/prefer-default-export`](https://github.com/import-js/eslint-plugin-import/blob/master/docs/rules/prefer-default-export.md) + > Why? To encourage more files that only ever export one thing, which is better for readability and maintainability. + + ```javascript + // bad + export function foo() {} + + // good + export default function foo() {} + ``` + + + - [10.7](#modules--imports-first) Put all `import`s above non-import statements. + eslint: [`import/first`](https://github.com/import-js/eslint-plugin-import/blob/master/docs/rules/first.md) + > Why? Since `import`s are hoisted, keeping them all at the top prevents surprising behavior. + + ```javascript + // bad + import foo from 'foo'; + foo.init(); + + import bar from 'bar'; + + // good + import foo from 'foo'; + import bar from 'bar'; + + foo.init(); + ``` + + + - [10.8](#modules--multiline-imports-over-newlines) Multiline imports should be indented just like multiline array and object literals. + eslint: [`object-curly-newline`](https://eslint.org/docs/rules/object-curly-newline) + + > Why? The curly braces follow the same indentation rules as every other curly brace block in the style guide, as do the trailing commas. + + ```javascript + // bad + import {longNameA, longNameB, longNameC, longNameD, longNameE} from 'path'; + + // good + import { + longNameA, + longNameB, + longNameC, + longNameD, + longNameE, + } from 'path'; + ``` + + + - [10.9](#modules--no-webpack-loader-syntax) Disallow Webpack loader syntax in module import statements. + eslint: [`import/no-webpack-loader-syntax`](https://github.com/import-js/eslint-plugin-import/blob/master/docs/rules/no-webpack-loader-syntax.md) + > Why? Since using Webpack syntax in the imports couples the code to a module bundler. Prefer using the loader syntax in `webpack.config.js`. + + ```javascript + // bad + import fooSass from 'css!sass!foo.scss'; + import barCss from 'style!css!bar.css'; + + // good + import fooSass from 'foo.scss'; + import barCss from 'bar.css'; + ``` + + + - [10.10](#modules--import-extensions) Do not include JavaScript filename extensions + eslint: [`import/extensions`](https://github.com/import-js/eslint-plugin-import/blob/master/docs/rules/extensions.md) + > Why? Including extensions inhibits refactoring, and inappropriately hardcodes implementation details of the module you're importing in every consumer. + + ```javascript + // bad + import foo from './foo.js'; + import bar from './bar.jsx'; + import baz from './baz/index.jsx'; + + // good + import foo from './foo'; + import bar from './bar'; + import baz from './baz'; + ``` + +**[⬆ back to top](#table-of-contents)** + +## Iterators and Generators + + + - [11.1](#iterators--nope) Don’t use iterators. Prefer JavaScript’s higher-order functions instead of loops like `for-in` or `for-of`. eslint: [`no-iterator`](https://eslint.org/docs/rules/no-iterator) [`no-restricted-syntax`](https://eslint.org/docs/rules/no-restricted-syntax) + + > Why? This enforces our immutable rule. Dealing with pure functions that return values is easier to reason about than side effects. + + > Use `map()` / `every()` / `filter()` / `find()` / `findIndex()` / `reduce()` / `some()` / ... to iterate over arrays, and `Object.keys()` / `Object.values()` / `Object.entries()` to produce arrays so you can iterate over objects. + + ```javascript + const numbers = [1, 2, 3, 4, 5]; + + // bad + let sum = 0; + for (let num of numbers) { + sum += num; + } + sum === 15; + + // good + let sum = 0; + numbers.forEach((num) => { + sum += num; + }); + sum === 15; + + // best (use the functional force) + const sum = numbers.reduce((total, num) => total + num, 0); + sum === 15; + + // bad + const increasedByOne = []; + for (let i = 0; i < numbers.length; i++) { + increasedByOne.push(numbers[i] + 1); + } + + // good + const increasedByOne = []; + numbers.forEach((num) => { + increasedByOne.push(num + 1); + }); + + // best (keeping it functional) + const increasedByOne = numbers.map((num) => num + 1); + ``` + + + - [11.2](#generators--nope) Don’t use generators for now. + + > Why? They don’t transpile well to ES5. + + + - [11.3](#generators--spacing) If you must use generators, or if you disregard [our advice](#generators--nope), make sure their function signature is spaced properly. eslint: [`generator-star-spacing`](https://eslint.org/docs/rules/generator-star-spacing) + + > Why? `function` and `*` are part of the same conceptual keyword - `*` is not a modifier for `function`, `function*` is a unique construct, different from `function`. + + ```javascript + // bad + function * foo() { + // ... + } + + // bad + const bar = function * () { + // ... + }; + + // bad + const baz = function *() { + // ... + }; + + // bad + const quux = function*() { + // ... + }; + + // bad + function*foo() { + // ... + } + + // bad + function *foo() { + // ... + } + + // very bad + function + * + foo() { + // ... + } + + // very bad + const wat = function + * + () { + // ... + }; + + // good + function* foo() { + // ... + } + + // good + const foo = function* () { + // ... + }; + ``` + +**[⬆ back to top](#table-of-contents)** + +## Properties + + + - [12.1](#properties--dot) Use dot notation when accessing properties. eslint: [`dot-notation`](https://eslint.org/docs/rules/dot-notation) + + ```javascript + const luke = { + jedi: true, + age: 28, + }; + + // bad + const isJedi = luke['jedi']; + + // good + const isJedi = luke.jedi; + ``` + + + - [12.2](#properties--bracket) Use bracket notation `[]` when accessing properties with a variable. + + ```javascript + const luke = { + jedi: true, + age: 28, + }; + + function getProp(prop) { + return luke[prop]; + } + + const isJedi = getProp('jedi'); + ``` + + + - [12.3](#es2016-properties--exponentiation-operator) Use exponentiation operator `**` when calculating exponentiations. eslint: [`prefer-exponentiation-operator`](https://eslint.org/docs/rules/prefer-exponentiation-operator). + + ```javascript + // bad + const binary = Math.pow(2, 10); + + // good + const binary = 2 ** 10; + ``` + +**[⬆ back to top](#table-of-contents)** + +## Variables + + + - [13.1](#variables--const) Always use `const` or `let` to declare variables. Not doing so will result in global variables. We want to avoid polluting the global namespace. Captain Planet warned us of that. eslint: [`no-undef`](https://eslint.org/docs/rules/no-undef) [`prefer-const`](https://eslint.org/docs/rules/prefer-const) + + ```javascript + // bad + superPower = new SuperPower(); + + // good + const superPower = new SuperPower(); + ``` + + + - [13.2](#variables--one-const) Use one `const` or `let` declaration per variable or assignment. eslint: [`one-var`](https://eslint.org/docs/rules/one-var) + + > Why? It’s easier to add new variable declarations this way, and you never have to worry about swapping out a `;` for a `,` or introducing punctuation-only diffs. You can also step through each declaration with the debugger, instead of jumping through all of them at once. + + ```javascript + // bad + const items = getItems(), + goSportsTeam = true, + dragonball = 'z'; + + // bad + // (compare to above, and try to spot the mistake) + const items = getItems(), + goSportsTeam = true; + dragonball = 'z'; + + // good + const items = getItems(); + const goSportsTeam = true; + const dragonball = 'z'; + ``` + + + - [13.3](#variables--const-let-group) Group all your `const`s and then group all your `let`s. + + > Why? This is helpful when later on you might need to assign a variable depending on one of the previously assigned variables. + + ```javascript + // bad + let i, len, dragonball, + items = getItems(), + goSportsTeam = true; + + // bad + let i; + const items = getItems(); + let dragonball; + const goSportsTeam = true; + let len; + + // good + const goSportsTeam = true; + const items = getItems(); + let dragonball; + let i; + let length; + ``` + + + - [13.4](#variables--define-where-used) Assign variables where you need them, but place them in a reasonable place. + + > Why? `let` and `const` are block scoped and not function scoped. + + ```javascript + // bad - unnecessary function call + function checkName(hasName) { + const name = getName(); + + if (hasName === 'test') { + return false; + } + + if (name === 'test') { + this.setName(''); + return false; + } + + return name; + } + + // good + function checkName(hasName) { + if (hasName === 'test') { + return false; + } + + const name = getName(); + + if (name === 'test') { + this.setName(''); + return false; + } + + return name; + } + ``` + + + - [13.5](#variables--no-chain-assignment) Don’t chain variable assignments. eslint: [`no-multi-assign`](https://eslint.org/docs/rules/no-multi-assign) + + > Why? Chaining variable assignments creates implicit global variables. + + ```javascript + // bad + (function example() { + // JavaScript interprets this as + // let a = ( b = ( c = 1 ) ); + // The let keyword only applies to variable a; variables b and c become + // global variables. + let a = b = c = 1; + }()); + + console.log(a); // throws ReferenceError + console.log(b); // 1 + console.log(c); // 1 + + // good + (function example() { + let a = 1; + let b = a; + let c = a; + }()); + + console.log(a); // throws ReferenceError + console.log(b); // throws ReferenceError + console.log(c); // throws ReferenceError + + // the same applies for `const` + ``` + + + - [13.6](#variables--unary-increment-decrement) Avoid using unary increments and decrements (`++`, `--`). eslint [`no-plusplus`](https://eslint.org/docs/rules/no-plusplus) + + > Why? Per the eslint documentation, unary increment and decrement statements are subject to automatic semicolon insertion and can cause silent errors with incrementing or decrementing values within an application. It is also more expressive to mutate your values with statements like `num += 1` instead of `num++` or `num ++`. Disallowing unary increment and decrement statements also prevents you from pre-incrementing/pre-decrementing values unintentionally which can also cause unexpected behavior in your programs. + + ```javascript + // bad + + const array = [1, 2, 3]; + let num = 1; + num++; + --num; + + let sum = 0; + let truthyCount = 0; + for (let i = 0; i < array.length; i++) { + let value = array[i]; + sum += value; + if (value) { + truthyCount++; + } + } + + // good + + const array = [1, 2, 3]; + let num = 1; + num += 1; + num -= 1; + + const sum = array.reduce((a, b) => a + b, 0); + const truthyCount = array.filter(Boolean).length; + ``` + + + - [13.7](#variables--linebreak) Avoid linebreaks before or after `=` in an assignment. If your assignment violates [`max-len`](https://eslint.org/docs/rules/max-len), surround the value in parens. eslint [`operator-linebreak`](https://eslint.org/docs/rules/operator-linebreak). + + > Why? Linebreaks surrounding `=` can obfuscate the value of an assignment. + + ```javascript + // bad + const foo = + superLongLongLongLongLongLongLongLongFunctionName(); + + // bad + const foo + = 'superLongLongLongLongLongLongLongLongString'; + + // good + const foo = ( + superLongLongLongLongLongLongLongLongFunctionName() + ); + + // good + const foo = 'superLongLongLongLongLongLongLongLongString'; + ``` + + + - [13.8](#variables--no-unused-vars) Disallow unused variables. eslint: [`no-unused-vars`](https://eslint.org/docs/rules/no-unused-vars) + + > Why? Variables that are declared and not used anywhere in the code are most likely an error due to incomplete refactoring. Such variables take up space in the code and can lead to confusion by readers. + + ```javascript + // bad + + const some_unused_var = 42; + + // Write-only variables are not considered as used. + let y = 10; + y = 5; + + // A read for a modification of itself is not considered as used. + let z = 0; + z = z + 1; + + // Unused function arguments. + function getX(x, y) { + return x; + } + + // good + + function getXPlusY(x, y) { + return x + y; + } + + const x = 1; + const y = a + 2; + + alert(getXPlusY(x, y)); + + // 'type' is ignored even if unused because it has a rest property sibling. + // This is a form of extracting an object that omits the specified keys. + const { type, ...coords } = data; + // 'coords' is now the 'data' object without its 'type' property. + ``` + +**[⬆ back to top](#table-of-contents)** + +## Hoisting + + + - [14.1](#hoisting--about) `var` declarations get hoisted to the top of their closest enclosing function scope, their assignment does not. `const` and `let` declarations are blessed with a new concept called [Temporal Dead Zones (TDZ)](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/let#temporal_dead_zone_tdz). It’s important to know why [typeof is no longer safe](https://web.archive.org/web/20200121061528/http://es-discourse.com/t/why-typeof-is-no-longer-safe/15). + + ```javascript + // we know this wouldn’t work (assuming there + // is no notDefined global variable) + function example() { + console.log(notDefined); // => throws a ReferenceError + } + + // creating a variable declaration after you + // reference the variable will work due to + // variable hoisting. Note: the assignment + // value of `true` is not hoisted. + function example() { + console.log(declaredButNotAssigned); // => undefined + var declaredButNotAssigned = true; + } + + // the interpreter is hoisting the variable + // declaration to the top of the scope, + // which means our example could be rewritten as: + function example() { + let declaredButNotAssigned; + console.log(declaredButNotAssigned); // => undefined + declaredButNotAssigned = true; + } + + // using const and let + function example() { + console.log(declaredButNotAssigned); // => throws a ReferenceError + console.log(typeof declaredButNotAssigned); // => throws a ReferenceError + const declaredButNotAssigned = true; + } + ``` + + + - [14.2](#hoisting--anon-expressions) Anonymous function expressions hoist their variable name, but not the function assignment. + + ```javascript + function example() { + console.log(anonymous); // => undefined + + anonymous(); // => TypeError anonymous is not a function + + var anonymous = function () { + console.log('anonymous function expression'); + }; + } + ``` + + + - [14.3](#hoisting--named-expressions) Named function expressions hoist the variable name, not the function name or the function body. + + ```javascript + function example() { + console.log(named); // => undefined + + named(); // => TypeError named is not a function + + superPower(); // => ReferenceError superPower is not defined + + var named = function superPower() { + console.log('Flying'); + }; + } + + // the same is true when the function name + // is the same as the variable name. + function example() { + console.log(named); // => undefined + + named(); // => TypeError named is not a function + + var named = function named() { + console.log('named'); + }; + } + ``` + + + - [14.4](#hoisting--declarations) Function declarations hoist their name and the function body. + + ```javascript + function example() { + superPower(); // => Flying + + function superPower() { + console.log('Flying'); + } + } + ``` + + + - [14.5](#no-use-before-define) Variables, classes, and functions should be defined before they can be used. eslint: [`no-use-before-define`](https://eslint.org/docs/latest/rules/no-use-before-define) + + > Why? When variables, classes, or functions are declared after being used, it can harm readability since a reader won't know what a thing that's referenced is. It's much clearer for a reader to first encounter the source of a thing (whether imported from another module, or defined in the file) before encountering a use of the thing. + + ```javascript + // bad + + // Variable a is being used before it is being defined. + console.log(a); // this will be undefined, since while the declaration is hoisted, the initialization is not + var a = 10; + + // Function fun is being called before being defined. + fun(); + function fun() {} + + // Class A is being used before being defined. + new A(); // ReferenceError: Cannot access 'A' before initialization + class A { + } + + // `let` and `const` are hoisted, but they don't have a default initialization. + // The variables 'a' and 'b' are in a Temporal Dead Zone where JavaScript + // knows they exist (declaration is hoisted) but they are not accessible + // (as they are not yet initialized). + + console.log(a); // ReferenceError: Cannot access 'a' before initialization + console.log(b); // ReferenceError: Cannot access 'b' before initialization + let a = 10; + const b = 5; + + + // good + + var a = 10; + console.log(a); // 10 + + function fun() {} + fun(); + + class A { + } + new A(); + + let a = 10; + const b = 5; + console.log(a); // 10 + console.log(b); // 5 + ``` + + - For more information refer to [JavaScript Scoping & Hoisting](https://www.adequatelygood.com/2010/2/JavaScript-Scoping-and-Hoisting/) by [Ben Cherry](https://www.adequatelygood.com/). + +**[⬆ back to top](#table-of-contents)** + +## Comparison Operators & Equality + + + - [15.1](#comparison--eqeqeq) Use `===` and `!==` over `==` and `!=`. eslint: [`eqeqeq`](https://eslint.org/docs/rules/eqeqeq) + + + - [15.2](#comparison--if) Conditional statements such as the `if` statement evaluate their expression using coercion with the `ToBoolean` abstract method and always follow these simple rules: + + - **Objects** evaluate to **true** + - **Undefined** evaluates to **false** + - **Null** evaluates to **false** + - **Booleans** evaluate to **the value of the boolean** + - **Numbers** evaluate to **false** if **+0, -0, or NaN**, otherwise **true** + - **Strings** evaluate to **false** if an empty string `''`, otherwise **true** + + ```javascript + if ([0] && []) { + // true + // an array (even an empty one) is an object, objects will evaluate to true + } + ``` + + + - [15.3](#comparison--shortcuts) Use shortcuts for booleans, but explicit comparisons for strings and numbers. + + ```javascript + // bad + if (isValid === true) { + // ... + } + + // good + if (isValid) { + // ... + } + + // bad + if (name) { + // ... + } + + // good + if (name !== '') { + // ... + } + + // bad + if (collection.length) { + // ... + } + + // good + if (collection.length > 0) { + // ... + } + ``` + + + - [15.4](#comparison--moreinfo) For more information see [Truth, Equality, and JavaScript](https://javascriptweblog.wordpress.com/2011/02/07/truth-equality-and-javascript/#more-2108) by Angus Croll. + + + - [15.5](#comparison--switch-blocks) Use braces to create blocks in `case` and `default` clauses that contain lexical declarations (e.g. `let`, `const`, `function`, and `class`). eslint: [`no-case-declarations`](https://eslint.org/docs/rules/no-case-declarations) + + > Why? Lexical declarations are visible in the entire `switch` block but only get initialized when assigned, which only happens when its `case` is reached. This causes problems when multiple `case` clauses attempt to define the same thing. + + ```javascript + // bad + switch (foo) { + case 1: + let x = 1; + break; + case 2: + const y = 2; + break; + case 3: + function f() { + // ... + } + break; + default: + class C {} + } + + // good + switch (foo) { + case 1: { + let x = 1; + break; + } + case 2: { + const y = 2; + break; + } + case 3: { + function f() { + // ... + } + break; + } + case 4: + bar(); + break; + default: { + class C {} + } + } + ``` + + + - [15.6](#comparison--nested-ternaries) Ternaries should not be nested and generally be single line expressions. eslint: [`no-nested-ternary`](https://eslint.org/docs/rules/no-nested-ternary) + + ```javascript + // bad + const foo = maybe1 > maybe2 + ? "bar" + : value1 > value2 ? "baz" : null; + + // split into 2 separated ternary expressions + const maybeNull = value1 > value2 ? 'baz' : null; + + // better + const foo = maybe1 > maybe2 + ? 'bar' + : maybeNull; + + // best + const foo = maybe1 > maybe2 ? 'bar' : maybeNull; + ``` + + + - [15.7](#comparison--unneeded-ternary) Avoid unneeded ternary statements. eslint: [`no-unneeded-ternary`](https://eslint.org/docs/rules/no-unneeded-ternary) + + ```javascript + // bad + const foo = a ? a : b; + const bar = c ? true : false; + const baz = c ? false : true; + const quux = a != null ? a : b; + + // good + const foo = a || b; + const bar = !!c; + const baz = !c; + const quux = a ?? b; + ``` + + + - [15.8](#comparison--no-mixed-operators) When mixing operators, enclose them in parentheses. The only exception is the standard arithmetic operators: `+`, `-`, and `**` since their precedence is broadly understood. We recommend enclosing `/` and `*` in parentheses because their precedence can be ambiguous when they are mixed. + eslint: [`no-mixed-operators`](https://eslint.org/docs/rules/no-mixed-operators) + + > Why? This improves readability and clarifies the developer’s intention. + + ```javascript + // bad + const foo = a && b < 0 || c > 0 || d + 1 === 0; + + // bad + const bar = a ** b - 5 % d; + + // bad + // one may be confused into thinking (a || b) && c + if (a || b && c) { + return d; + } + + // bad + const bar = a + b / c * d; + + // good + const foo = (a && b < 0) || c > 0 || (d + 1 === 0); + + // good + const bar = a ** b - (5 % d); + + // good + if (a || (b && c)) { + return d; + } + + // good + const bar = a + (b / c) * d; + ``` + + + - [15.9](#nullish-coalescing-operator) The nullish coalescing operator (`??`) is a logical operator that returns its right-hand side operand when its left-hand side operand is `null` or `undefined`. Otherwise, it returns the left-hand side operand. + + > Why? It provides precision by distinguishing null/undefined from other falsy values, enhancing code clarity and predictability. + + ```javascript + // bad + const value = 0 ?? 'default'; + // returns 0, not 'default' + + // bad + const value = '' ?? 'default'; + // returns '', not 'default' + + // good + const value = null ?? 'default'; + // returns 'default' + + // good + const user = { + name: 'John', + age: null + }; + const age = user.age ?? 18; + // returns 18 + ``` + +**[⬆ back to top](#table-of-contents)** + +## Blocks + + + - [16.1](#blocks--braces) Use braces with all multiline blocks. eslint: [`nonblock-statement-body-position`](https://eslint.org/docs/rules/nonblock-statement-body-position) + + ```javascript + // bad + if (test) + return false; + + // good + if (test) return false; + + // good + if (test) { + return false; + } + + // bad + function foo() { return false; } + + // good + function bar() { + return false; + } + ``` + + + - [16.2](#blocks--cuddled-elses) If you’re using multiline blocks with `if` and `else`, put `else` on the same line as your `if` block’s closing brace. eslint: [`brace-style`](https://eslint.org/docs/rules/brace-style) + + ```javascript + // bad + if (test) { + thing1(); + thing2(); + } + else { + thing3(); + } + + // good + if (test) { + thing1(); + thing2(); + } else { + thing3(); + } + ``` + + + - [16.3](#blocks--no-else-return) If an `if` block always executes a `return` statement, the subsequent `else` block is unnecessary. A `return` in an `else if` block following an `if` block that contains a `return` can be separated into multiple `if` blocks. eslint: [`no-else-return`](https://eslint.org/docs/rules/no-else-return) + + ```javascript + // bad + function foo() { + if (x) { + return x; + } else { + return y; + } + } + + // bad + function cats() { + if (x) { + return x; + } else if (y) { + return y; + } + } + + // bad + function dogs() { + if (x) { + return x; + } else { + if (y) { + return y; + } + } + } + + // good + function foo() { + if (x) { + return x; + } + + return y; + } + + // good + function cats() { + if (x) { + return x; + } + + if (y) { + return y; + } + } + + // good + function dogs(x) { + if (x) { + if (z) { + return y; + } + } else { + return z; + } + } + ``` + +**[⬆ back to top](#table-of-contents)** + +## Control Statements + + + - [17.1](#control-statements) In case your control statement (`if`, `while` etc.) gets too long or exceeds the maximum line length, each (grouped) condition could be put into a new line. The logical operator should begin the line. + + > Why? Requiring operators at the beginning of the line keeps the operators aligned and follows a pattern similar to method chaining. This also improves readability by making it easier to visually follow complex logic. + + ```javascript + // bad + if ((foo === 123 || bar === 'abc') && doesItLookGoodWhenItBecomesThatLong() && isThisReallyHappening()) { + thing1(); + } + + // bad + if (foo === 123 && + bar === 'abc') { + thing1(); + } + + // bad + if (foo === 123 + && bar === 'abc') { + thing1(); + } + + // bad + if ( + foo === 123 && + bar === 'abc' + ) { + thing1(); + } // good - if (test) return false; + if ( + foo === 123 + && bar === 'abc' + ) { + thing1(); + } // good - if (test) { - return false; + if ( + (foo === 123 || bar === 'abc') + && doesItLookGoodWhenItBecomesThatLong() + && isThisReallyHappening() + ) { + thing1(); + } + + // good + if (foo === 123 && bar === 'abc') { + thing1(); } + ``` + + + - [17.2](#control-statements--value-selection) Don't use selection operators in place of control statements. + ```javascript // bad - function() { return false; } + !isRunning && startRunning(); // good - function() { - return false; + if (!isRunning) { + startRunning(); } ``` - **[[⬆]](#TOC)** +**[⬆ back to top](#table-of-contents)** +## Comments -## Comments - - - Use `/** ... */` for multiline comments. Include a description, specify types and values for all parameters and return values. + + - [18.1](#comments--multiline) Use `/** ... */` for multiline comments. ```javascript // bad // make() returns a new element // based on the passed in tag name // - // @param tag - // @return element + // @param {String} tag + // @return {Element} element function make(tag) { - // ...stuff... + // ... return element; } @@ -653,34 +2440,32 @@ // good /** * make() returns a new element - * based on the passed in tag name - * - * @param tag - * @return element + * based on the passed-in tag name */ function make(tag) { - // ...stuff... + // ... return element; } ``` - - Use `//` for single line comments. Place single line comments on a newline above the subject of the comment. Put an empty line before the comment. + + - [18.2](#comments--singleline) Use `//` for single line comments. Place single line comments on a newline above the subject of the comment. Put an empty line before the comment unless it’s on the first line of a block. ```javascript // bad - var active = true; // is current tab + const active = true; // is current tab // good // is current tab - var active = true; + const active = true; // bad function getType() { console.log('fetching type...'); // set the default type to 'no type' - var type = this._type || 'no type'; + const type = this.type || 'no type'; return type; } @@ -690,285 +2475,828 @@ console.log('fetching type...'); // set the default type to 'no type' - var type = this._type || 'no type'; + const type = this.type || 'no type'; + + return type; + } + + // also good + function getType() { + // set the default type to 'no type' + const type = this.type || 'no type'; return type; } ``` - - Prefixing your comments with `FIXME` or `TODO` helps other developers quickly understand if you're pointing out a problem that needs to be revisited, or if you're suggesting a solution to the problem that needs to be implemented. These are different than regular comments because they are actionable. The actions are `FIXME -- need to figure this out` or `TODO -- need to implement`. + + - [18.3](#comments--spaces) Start all comments with a space to make it easier to read. eslint: [`spaced-comment`](https://eslint.org/docs/rules/spaced-comment) + + ```javascript + // bad + //is current tab + const active = true; + + // good + // is current tab + const active = true; + + // bad + /** + *make() returns a new element + *based on the passed-in tag name + */ + function make(tag) { + + // ... + + return element; + } + + // good + /** + * make() returns a new element + * based on the passed-in tag name + */ + function make(tag) { + + // ... + + return element; + } + ``` + + + - [18.4](#comments--actionitems) Prefixing your comments with `FIXME` or `TODO` helps other developers quickly understand if you’re pointing out a problem that needs to be revisited, or if you’re suggesting a solution to the problem that needs to be implemented. These are different than regular comments because they are actionable. The actions are `FIXME: -- need to figure this out` or `TODO: -- need to implement`. + + + - [18.5](#comments--fixme) Use `// FIXME:` to annotate problems. + + ```javascript + class Calculator extends Abacus { + constructor() { + super(); + + // FIXME: shouldn’t use a global here + total = 0; + } + } + ``` + + + - [18.6](#comments--todo) Use `// TODO:` to annotate solutions to problems. + + ```javascript + class Calculator extends Abacus { + constructor() { + super(); + + // TODO: total should be configurable by an options param + this.total = 0; + } + } + ``` + +**[⬆ back to top](#table-of-contents)** + +## Whitespace + + + - [19.1](#whitespace--spaces) Use soft tabs (space character) set to 2 spaces. eslint: [`indent`](https://eslint.org/docs/rules/indent) + + ```javascript + // bad + function foo() { + ∙∙∙∙let name; + } + + // bad + function bar() { + ∙let name; + } + + // good + function baz() { + ∙∙let name; + } + ``` + + + - [19.2](#whitespace--before-blocks) Place 1 space before the leading brace. eslint: [`space-before-blocks`](https://eslint.org/docs/rules/space-before-blocks) + + ```javascript + // bad + function test(){ + console.log('test'); + } + + // good + function test() { + console.log('test'); + } + + // bad + dog.set('attr',{ + age: '1 year', + breed: 'Bernese Mountain Dog', + }); + + // good + dog.set('attr', { + age: '1 year', + breed: 'Bernese Mountain Dog', + }); + ``` + + + - [19.3](#whitespace--around-keywords) Place 1 space before the opening parenthesis in control statements (`if`, `while` etc.). Place no space between the argument list and the function name in function calls and declarations. eslint: [`keyword-spacing`](https://eslint.org/docs/rules/keyword-spacing) + + ```javascript + // bad + if(isJedi) { + fight (); + } + + // good + if (isJedi) { + fight(); + } + + // bad + function fight () { + console.log ('Swooosh!'); + } + + // good + function fight() { + console.log('Swooosh!'); + } + ``` + + + - [19.4](#whitespace--infix-ops) Set off operators with spaces. eslint: [`space-infix-ops`](https://eslint.org/docs/rules/space-infix-ops) + + ```javascript + // bad + const x=y+5; + + // good + const x = y + 5; + ``` + + + - [19.5](#whitespace--newline-at-end) End files with a single newline character. eslint: [`eol-last`](https://eslint.org/docs/rules/eol-last) + + ```javascript + // bad + import { es6 } from './AirbnbStyleGuide'; + // ... + export default es6; + ``` + + ```javascript + // bad + import { es6 } from './AirbnbStyleGuide'; + // ... + export default es6;↵ + ↵ + ``` + + ```javascript + // good + import { es6 } from './AirbnbStyleGuide'; + // ... + export default es6;↵ + ``` + + + - [19.6](#whitespace--chains) Use indentation when making long method chains (more than 2 method chains). Use a leading dot, which + emphasizes that the line is a method call, not a new statement. eslint: [`newline-per-chained-call`](https://eslint.org/docs/rules/newline-per-chained-call) [`no-whitespace-before-property`](https://eslint.org/docs/rules/no-whitespace-before-property) + + ```javascript + // bad + $('#items').find('.selected').highlight().end().find('.open').updateCount(); + + // bad + $('#items'). + find('.selected'). + highlight(). + end(). + find('.open'). + updateCount(); + + // good + $('#items') + .find('.selected') + .highlight() + .end() + .find('.open') + .updateCount(); + + // bad + const leds = stage.selectAll('.led').data(data).enter().append('svg:svg').classed('led', true) + .attr('width', (radius + margin) * 2).append('svg:g') + .attr('transform', `translate(${radius + margin}, ${radius + margin})`) + .call(tron.led); + + // good + const leds = stage.selectAll('.led') + .data(data) + .enter().append('svg:svg') + .classed('led', true) + .attr('width', (radius + margin) * 2) + .append('svg:g') + .attr('transform', `translate(${radius + margin}, ${radius + margin})`) + .call(tron.led); + + // good + const leds = stage.selectAll('.led').data(data); + const svg = leds.enter().append('svg:svg'); + svg.classed('led', true).attr('width', (radius + margin) * 2); + const g = svg.append('svg:g'); + g.attr('transform', `translate(${radius + margin}, ${radius + margin})`).call(tron.led); + ``` + + + - [19.7](#whitespace--after-blocks) Leave a blank line after blocks and before the next statement. + + ```javascript + // bad + if (foo) { + return bar; + } + return baz; + + // good + if (foo) { + return bar; + } + + return baz; + + // bad + const obj = { + foo() { + }, + bar() { + }, + }; + return obj; + + // good + const obj = { + foo() { + }, + + bar() { + }, + }; + + return obj; + + // bad + const arr = [ + function foo() { + }, + function bar() { + }, + ]; + return arr; + + // good + const arr = [ + function foo() { + }, + + function bar() { + }, + ]; + + return arr; + ``` + + + - [19.8](#whitespace--padded-blocks) Do not pad your blocks with blank lines. eslint: [`padded-blocks`](https://eslint.org/docs/rules/padded-blocks) + + ```javascript + // bad + function bar() { + + console.log(foo); + + } + + // bad + if (baz) { + + console.log(quux); + } else { + console.log(foo); + + } + + // bad + class Foo { + + constructor(bar) { + this.bar = bar; + } + } + + // good + function bar() { + console.log(foo); + } + + // good + if (baz) { + console.log(quux); + } else { + console.log(foo); + } + ``` + + + - [19.9](#whitespace--no-multiple-blanks) Do not use multiple blank lines to pad your code. eslint: [`no-multiple-empty-lines`](https://eslint.org/docs/rules/no-multiple-empty-lines) + + + ```javascript + // bad + class Person { + constructor(fullName, email, birthday) { + this.fullName = fullName; + + + this.email = email; + + + this.setAge(birthday); + } + + + setAge(birthday) { + const today = new Date(); + + + const age = this.getAge(today, birthday); + + + this.age = age; + } + + + getAge(today, birthday) { + // .. + } + } + + // good + class Person { + constructor(fullName, email, birthday) { + this.fullName = fullName; + this.email = email; + this.setAge(birthday); + } + + setAge(birthday) { + const today = new Date(); + const age = getAge(today, birthday); + this.age = age; + } + + getAge(today, birthday) { + // .. + } + } + ``` - - Use `// FIXME:` to annotate problems + + - [19.10](#whitespace--in-parens) Do not add spaces inside parentheses. eslint: [`space-in-parens`](https://eslint.org/docs/rules/space-in-parens) ```javascript - function Calculator() { + // bad + function bar( foo ) { + return foo; + } + + // good + function bar(foo) { + return foo; + } - // FIXME: shouldn't use a global here - total = 0; + // bad + if ( foo ) { + console.log(foo); + } - return this; + // good + if (foo) { + console.log(foo); } ``` - - Use `// TODO:` to annotate solutions to problems + + - [19.11](#whitespace--in-brackets) Do not add spaces inside brackets. eslint: [`array-bracket-spacing`](https://eslint.org/docs/rules/array-bracket-spacing) ```javascript - function Calculator() { + // bad + const foo = [ 1, 2, 3 ]; + console.log(foo[ 0 ]); - // TODO: total should be configurable by an options param - this.total = 0; + // good + const foo = [1, 2, 3]; + console.log(foo[0]); + ``` - return this; - } - ``` + + - [19.12](#whitespace--in-braces) Add spaces inside curly braces. eslint: [`object-curly-spacing`](https://eslint.org/docs/rules/object-curly-spacing) - **[[⬆]](#TOC)** + ```javascript + // bad + const foo = {clark: 'kent'}; + // good + const foo = { clark: 'kent' }; + ``` -## Whitespace + + - [19.13](#whitespace--max-len) Avoid having lines of code that are longer than 100 characters (including whitespace). Note: per [above](#strings--line-length), long strings are exempt from this rule, and should not be broken up. eslint: [`max-len`](https://eslint.org/docs/rules/max-len) - - Use soft tabs set to 2 spaces + > Why? This ensures readability and maintainability. ```javascript // bad - function() { - ∙∙∙∙var name; - } + const foo = jsonData && jsonData.foo && jsonData.foo.bar && jsonData.foo.bar.baz && jsonData.foo.bar.baz.quux && jsonData.foo.bar.baz.quux.xyzzy; // bad - function() { - ∙var name; - } + $.ajax({ method: 'POST', url: 'https://airbnb.com/', data: { name: 'John' } }).done(() => console.log('Congratulations!')).fail(() => console.log('You have failed this city.')); // good - function() { - ∙∙var name; - } + const foo = jsonData + && jsonData.foo + && jsonData.foo.bar + && jsonData.foo.bar.baz + && jsonData.foo.bar.baz.quux + && jsonData.foo.bar.baz.quux.xyzzy; + + // better + const foo = jsonData + ?.foo + ?.bar + ?.baz + ?.quux + ?.xyzzy; + + // good + $.ajax({ + method: 'POST', + url: 'https://airbnb.com/', + data: { name: 'John' }, + }) + .done(() => console.log('Congratulations!')) + .fail(() => console.log('You have failed this city.')); ``` - - Place 1 space before the leading brace. + + - [19.14](#whitespace--block-spacing) Require consistent spacing inside an open block token and the next token on the same line. This rule also enforces consistent spacing inside a close block token and previous token on the same line. eslint: [`block-spacing`](https://eslint.org/docs/rules/block-spacing) ```javascript // bad - function test(){ - console.log('test'); - } + function foo() {return true;} + if (foo) { bar = 0;} // good - function test() { - console.log('test'); - } + function foo() { return true; } + if (foo) { bar = 0; } + ``` + + - [19.15](#whitespace--comma-spacing) Avoid spaces before commas and require a space after commas. eslint: [`comma-spacing`](https://eslint.org/docs/rules/comma-spacing) + + ```javascript // bad - dog.set('attr',{ - age: '1 year', - breed: 'Bernese Mountain Dog' - }); + const foo = 1,bar = 2; + const arr = [1 , 2]; // good - dog.set('attr', { - age: '1 year', - breed: 'Bernese Mountain Dog' - }); + const foo = 1, bar = 2; + const arr = [1, 2]; ``` - - Set off operators with spaces. + + - [19.16](#whitespace--computed-property-spacing) Enforce spacing inside of computed property brackets. eslint: [`computed-property-spacing`](https://eslint.org/docs/rules/computed-property-spacing) ```javascript // bad - var x=y+5; + obj[foo ] + obj[ 'foo'] + const x = {[ b ]: a} + obj[foo[ bar ]] // good - var x = y + 5; + obj[foo] + obj['foo'] + const x = { [b]: a } + obj[foo[bar]] ``` - - Place an empty newline at the end of the file. + + - [19.17](#whitespace--func-call-spacing) Avoid spaces between functions and their invocations. eslint: [`func-call-spacing`](https://eslint.org/docs/rules/func-call-spacing) ```javascript // bad - (function(global) { - // ...stuff... - })(this); - ``` + func (); - ```javascript - // good - (function(global) { - // ...stuff... - })(this); + func + (); + // good + func(); ``` - - Use indentation when making long method chains. + + - [19.18](#whitespace--key-spacing) Enforce spacing between keys and values in object literal properties. eslint: [`key-spacing`](https://eslint.org/docs/rules/key-spacing) ```javascript // bad - $('#items').find('.selected').highlight().end().find('.open').updateCount(); + const obj = { foo : 42 }; + const obj2 = { foo:42 }; // good - $('#items') - .find('.selected') - .highlight() - .end() - .find('.open') - .updateCount(); + const obj = { foo: 42 }; + ``` - // bad - var leds = stage.selectAll('.led').data(data).enter().append('svg:svg').class('led', true) - .attr('width', (radius + margin) * 2).append('svg:g') - .attr('transform', 'translate(' + (radius + margin) + ',' + (radius + margin) + ')') - .call(tron.led); + + - [19.19](#whitespace--no-trailing-spaces) Avoid trailing spaces at the end of lines. eslint: [`no-trailing-spaces`](https://eslint.org/docs/rules/no-trailing-spaces) + + + - [19.20](#whitespace--no-multiple-empty-lines) Avoid multiple empty lines, only allow one newline at the end of files, and avoid a newline at the beginning of files. eslint: [`no-multiple-empty-lines`](https://eslint.org/docs/rules/no-multiple-empty-lines) + + + ```javascript + // bad - multiple empty lines + const x = 1; + + + const y = 2; + + // bad - 2+ newlines at end of file + const x = 1; + const y = 2; + + + // bad - 1+ newline(s) at beginning of file + + const x = 1; + const y = 2; // good - var leds = stage.selectAll('.led') - .data(data) - .enter().append('svg:svg') - .class('led', true) - .attr('width', (radius + margin) * 2) - .append('svg:g') - .attr('transform', 'translate(' + (radius + margin) + ',' + (radius + margin) + ')') - .call(tron.led); + const x = 1; + const y = 2; + ``` + - **[[⬆]](#TOC)** +**[⬆ back to top](#table-of-contents)** -## Commas +## Commas - - Leading commas: **Nope.** + + - [20.1](#commas--leading-trailing) Leading commas: **Nope.** eslint: [`comma-style`](https://eslint.org/docs/rules/comma-style) ```javascript // bad - var once + const story = [ + once , upon - , aTime; + , aTime + ]; // good - var once, - upon, - aTime; + const story = [ + once, + upon, + aTime, + ]; // bad - var hero = { - firstName: 'Bob' - , lastName: 'Parr' - , heroName: 'Mr. Incredible' - , superPower: 'strength' + const hero = { + firstName: 'Ada' + , lastName: 'Lovelace' + , birthYear: 1815 + , superPower: 'computers' }; // good - var hero = { - firstName: 'Bob', - lastName: 'Parr', - heroName: 'Mr. Incredible', - superPower: 'strength' + const hero = { + firstName: 'Ada', + lastName: 'Lovelace', + birthYear: 1815, + superPower: 'computers', }; ``` - - Additional trailing comma: **Nope.** This can cause problems with IE6/7 and IE9 if it's in quirksmode. Also, in some implementations of ES3 would add length to an array if it had an additional trailing comma. This was clarified in ES5 ([source](http://es5.github.io/#D)): + + - [20.2](#commas--dangling) Additional trailing comma: **Yup.** eslint: [`comma-dangle`](https://eslint.org/docs/rules/comma-dangle) + + > Why? This leads to cleaner git diffs. Also, transpilers like Babel will remove the additional trailing comma in the transpiled code which means you don’t have to worry about the [trailing comma problem](https://github.com/airbnb/javascript/blob/es5-deprecated/es5/README.md#commas) in legacy browsers. + + ```diff + // bad - git diff without trailing comma + const hero = { + firstName: 'Florence', + - lastName: 'Nightingale' + + lastName: 'Nightingale', + + inventorOf: ['coxcomb chart', 'modern nursing'] + }; - > Edition 5 clarifies the fact that a trailing comma at the end of an ArrayInitialiser does not add to the length of the array. This is not a semantic change from Edition 3 but some implementations may have previously misinterpreted this. + // good - git diff with trailing comma + const hero = { + firstName: 'Florence', + lastName: 'Nightingale', + + inventorOf: ['coxcomb chart', 'modern nursing'], + }; + ``` ```javascript // bad - var hero = { - firstName: 'Kevin', - lastName: 'Flynn', + const hero = { + firstName: 'Dana', + lastName: 'Scully' }; - var heroes = [ + const heroes = [ 'Batman', - 'Superman', + 'Superman' ]; // good - var hero = { - firstName: 'Kevin', - lastName: 'Flynn' + const hero = { + firstName: 'Dana', + lastName: 'Scully', }; - var heroes = [ + const heroes = [ 'Batman', - 'Superman' + 'Superman', ]; + + // bad + function createHero( + firstName, + lastName, + inventorOf + ) { + // does nothing + } + + // good + function createHero( + firstName, + lastName, + inventorOf, + ) { + // does nothing + } + + // good (note that a comma must not appear after a "rest" element) + function createHero( + firstName, + lastName, + inventorOf, + ...heroArgs + ) { + // does nothing + } + + // bad + createHero( + firstName, + lastName, + inventorOf + ); + + // good + createHero( + firstName, + lastName, + inventorOf, + ); + + // good (note that a comma must not appear after a "rest" element) + createHero( + firstName, + lastName, + inventorOf, + ...heroArgs + ); ``` - **[[⬆]](#TOC)** +**[⬆ back to top](#table-of-contents)** +## Semicolons -## Semicolons + + - [21.1](#semicolons--required) **Yup.** eslint: [`semi`](https://eslint.org/docs/rules/semi) - - **Yup.** + > Why? When JavaScript encounters a line break without a semicolon, it uses a set of rules called [Automatic Semicolon Insertion](https://tc39.github.io/ecma262/#sec-automatic-semicolon-insertion) to determine whether it should regard that line break as the end of a statement, and (as the name implies) place a semicolon into your code before the line break if it thinks so. ASI contains a few eccentric behaviors, though, and your code will break if JavaScript misinterprets your line break. These rules will become more complicated as new features become a part of JavaScript. Explicitly terminating your statements and configuring your linter to catch missing semicolons will help prevent you from encountering issues. ```javascript - // bad - (function() { - var name = 'Skywalker' - return name - })() + // bad - raises exception + const luke = {} + const leia = {} + [luke, leia].forEach((jedi) => jedi.father = 'vader') + + // bad - raises exception + const reaction = "No! That’s impossible!" + (async function meanwhileOnTheFalcon() { + // handle `leia`, `lando`, `chewie`, `r2`, `c3p0` + // ... + }()) + + // bad - returns `undefined` instead of the value on the next line - always happens when `return` is on a line by itself because of ASI! + function foo() { + return + 'search your feelings, you know it to be foo' + } // good - (function() { - var name = 'Skywalker'; - return name; - })(); + const luke = {}; + const leia = {}; + [luke, leia].forEach((jedi) => { + jedi.father = 'vader'; + }); // good - ;(function() { - var name = 'Skywalker'; - return name; - })(); + const reaction = 'No! That’s impossible!'; + (async function meanwhileOnTheFalcon() { + // handle `leia`, `lando`, `chewie`, `r2`, `c3p0` + // ... + }()); + + // good + function foo() { + return 'search your feelings, you know it to be foo'; + } ``` - **[[⬆]](#TOC)** + [Read more](https://stackoverflow.com/questions/7365172/semicolon-before-self-invoking-function/7365214#7365214). + +**[⬆ back to top](#table-of-contents)** +## Type Casting & Coercion -## Type Casting & Coercion + + - [22.1](#coercion--explicit) Perform type coercion at the beginning of the statement. - - Perform type coercion at the beginning of the statement. - - Strings: + + - [22.2](#coercion--strings) Strings: eslint: [`no-new-wrappers`](https://eslint.org/docs/rules/no-new-wrappers) ```javascript - // => this.reviewScore = 9; + // => this.reviewScore = 9; // bad - var totalScore = this.reviewScore + ''; + const totalScore = new String(this.reviewScore); // typeof totalScore is "object" not "string" - // good - var totalScore = '' + this.reviewScore; + // bad + const totalScore = this.reviewScore + ''; // invokes this.reviewScore.valueOf() // bad - var totalScore = '' + this.reviewScore + ' total score'; + const totalScore = this.reviewScore.toString(); // isn’t guaranteed to return a string // good - var totalScore = this.reviewScore + ' total score'; + const totalScore = String(this.reviewScore); ``` - - Use `parseInt` for Numbers and always with a radix for type casting. + + - [22.3](#coercion--numbers) Numbers: Use `Number` for type casting and `parseInt` always with a radix for parsing strings. eslint: [`radix`](https://eslint.org/docs/rules/radix) [`no-new-wrappers`](https://eslint.org/docs/rules/no-new-wrappers) + + > Why? The `parseInt` function produces an integer value dictated by interpretation of the contents of the string argument according to the specified radix. Leading whitespace in string is ignored. If radix is `undefined` or `0`, it is assumed to be `10` except when the number begins with the character pairs `0x` or `0X`, in which case a radix of 16 is assumed. This differs from ECMAScript 3, which merely discouraged (but allowed) octal interpretation. Many implementations have not adopted this behavior as of 2013. And, because older browsers must be supported, always specify a radix. ```javascript - var inputValue = '4'; + const inputValue = '4'; // bad - var val = new Number(inputValue); + const val = new Number(inputValue); // bad - var val = +inputValue; + const val = +inputValue; // bad - var val = inputValue >> 0; + const val = inputValue >> 0; // bad - var val = parseInt(inputValue); + const val = parseInt(inputValue); // good - var val = Number(inputValue); + const val = Number(inputValue); // good - var val = parseInt(inputValue, 10); + const val = parseInt(inputValue, 10); ``` - - If for whatever reason you are doing something wild and `parseInt` is your bottleneck and need to use Bitshift for [performance reasons](http://jsperf.com/coercion-vs-casting/3), leave a comment explaining why and what you're doing. - - **Note:** Be careful when using bitshift operations. Numbers are represented as [64-bit values](http://es5.github.io/#x4.3.19), but Bitshift operations always return a 32-bit integer ([source](http://es5.github.io/#x11.7)). Bitshift can lead to unexpected behavior for integer values larger than 32 bits. [Discussion](https://github.com/airbnb/javascript/issues/109) + + - [22.4](#coercion--comment-deviations) If for whatever reason you are doing something wild and `parseInt` is your bottleneck and need to use Bitshift for [performance reasons](https://web.archive.org/web/20200414205431/https://jsperf.com/coercion-vs-casting/3), leave a comment explaining why and what you’re doing. ```javascript // good @@ -977,63 +3305,69 @@ * Bitshifting the String to coerce it to a * Number made it a lot faster. */ - var val = inputValue >> 0; + const val = inputValue >> 0; + ``` + + + - [22.5](#coercion--bitwise) **Note:** Be careful when using bitshift operations. Numbers are represented as [64-bit values](https://es5.github.io/#x4.3.19), but bitshift operations always return a 32-bit integer ([source](https://es5.github.io/#x11.7)). Bitshift can lead to unexpected behavior for integer values larger than 32 bits. [Discussion](https://github.com/airbnb/javascript/issues/109). Largest signed 32-bit Int is 2,147,483,647: + + ```javascript + 2147483647 >> 0; // => 2147483647 + 2147483648 >> 0; // => -2147483648 + 2147483649 >> 0; // => -2147483647 ``` - - Booleans: + + - [22.6](#coercion--booleans) Booleans: eslint: [`no-new-wrappers`](https://eslint.org/docs/rules/no-new-wrappers) ```javascript - var age = 0; + const age = 0; // bad - var hasAge = new Boolean(age); + const hasAge = new Boolean(age); // good - var hasAge = Boolean(age); + const hasAge = Boolean(age); - // good - var hasAge = !!age; + // best + const hasAge = !!age; ``` - **[[⬆]](#TOC)** +**[⬆ back to top](#table-of-contents)** +## Naming Conventions -## Naming Conventions - - - Avoid single letter names. Be descriptive with your naming. + + - [23.1](#naming--descriptive) Avoid single letter names. Be descriptive with your naming. eslint: [`id-length`](https://eslint.org/docs/rules/id-length) ```javascript // bad function q() { - // ...stuff... + // ... } // good function query() { - // ..stuff.. + // ... } ``` - - Use camelCase when naming objects, functions, and instances + + - [23.2](#naming--camelCase) Use camelCase when naming objects, functions, and instances. eslint: [`camelcase`](https://eslint.org/docs/rules/camelcase) ```javascript // bad - var OBJEcttsssss = {}; - var this_is_my_object = {}; - function c() {}; - var u = new user({ - name: 'Bob Parr' - }); + const OBJEcttsssss = {}; + const this_is_my_object = {}; + function c() {} // good - var thisIsMyObject = {}; - function thisIsMyFunction() {}; - var user = new User({ - name: 'Bob Parr' - }); + const thisIsMyObject = {}; + function thisIsMyFunction() {} ``` - - Use PascalCase when naming constructors or classes + + - [23.3](#naming--PascalCase) Use PascalCase only when naming constructors or classes. eslint: [`new-cap`](https://eslint.org/docs/rules/new-cap) ```javascript // bad @@ -1041,318 +3375,354 @@ this.name = options.name; } - var bad = new user({ - name: 'nope' + const bad = new user({ + name: 'nope', }); // good - function User(options) { - this.name = options.name; + class User { + constructor(options) { + this.name = options.name; + } } - var good = new User({ - name: 'yup' + const good = new User({ + name: 'yup', }); ``` - - Use a leading underscore `_` when naming private properties + + - [23.4](#naming--leading-underscore) Do not use trailing or leading underscores. eslint: [`no-underscore-dangle`](https://eslint.org/docs/rules/no-underscore-dangle) + + > Why? JavaScript does not have the concept of privacy in terms of properties or methods. Although a leading underscore is a common convention to mean “private”, in fact, these properties are fully public, and as such, are part of your public API contract. This convention might lead developers to wrongly think that a change won’t count as breaking, or that tests aren’t needed. tl;dr: if you want something to be “private”, it must not be observably present. ```javascript // bad this.__firstName__ = 'Panda'; this.firstName_ = 'Panda'; + this._firstName = 'Panda'; // good - this._firstName = 'Panda'; + this.firstName = 'Panda'; + + // good, in environments where WeakMaps are available + // see https://compat-table.github.io/compat-table/es6/#test-WeakMap + const firstNames = new WeakMap(); + firstNames.set(this, 'Panda'); ``` - - When saving a reference to `this` use `_this`. + + - [23.5](#naming--self-this) Don’t save references to `this`. Use arrow functions or [Function#bind](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/bind). ```javascript // bad - function() { - var self = this; - return function() { + function foo() { + const self = this; + return function () { console.log(self); }; } // bad - function() { - var that = this; - return function() { + function foo() { + const that = this; + return function () { console.log(that); }; } // good - function() { - var _this = this; - return function() { - console.log(_this); + function foo() { + return () => { + console.log(this); }; } ``` - - Name your functions. This is helpful for stack traces. + + - [23.6](#naming--filename-matches-export) A base filename should exactly match the name of its default export. ```javascript - // bad - var log = function(msg) { - console.log(msg); - }; - - // good - var log = function log(msg) { - console.log(msg); - }; - ``` - - **[[⬆]](#TOC)** - + // file 1 contents + class CheckBox { + // ... + } + export default CheckBox; -## Accessors + // file 2 contents + export default function fortyTwo() { return 42; } - - Accessor functions for properties are not required - - If you do make accessor functions use getVal() and setVal('hello') + // file 3 contents + export default function insideDirectory() {} - ```javascript + // in some other file // bad - dragon.age(); - - // good - dragon.getAge(); + import CheckBox from './checkBox'; // PascalCase import/export, camelCase filename + import FortyTwo from './FortyTwo'; // PascalCase import/filename, camelCase export + import InsideDirectory from './InsideDirectory'; // PascalCase import/filename, camelCase export // bad - dragon.age(25); + import CheckBox from './check_box'; // PascalCase import/export, snake_case filename + import forty_two from './forty_two'; // snake_case import/filename, camelCase export + import inside_directory from './inside_directory'; // snake_case import, camelCase export + import index from './inside_directory/index'; // requiring the index file explicitly + import insideDirectory from './insideDirectory/index'; // requiring the index file explicitly // good - dragon.setAge(25); + import CheckBox from './CheckBox'; // PascalCase export/import/filename + import fortyTwo from './fortyTwo'; // camelCase export/import/filename + import insideDirectory from './insideDirectory'; // camelCase export/import/directory name/implicit "index" + // ^ supports both insideDirectory.js and insideDirectory/index.js ``` - - If the property is a boolean, use isVal() or hasVal() + + - [23.7](#naming--camelCase-default-export) Use camelCase when you export-default a function. Your filename should be identical to your function’s name. ```javascript - // bad - if (!dragon.age()) { - return false; + function makeStyleGuide() { + // ... } - // good - if (!dragon.hasAge()) { - return false; - } + export default makeStyleGuide; ``` - - It's okay to create get() and set() functions, but be consistent. + + - [23.8](#naming--PascalCase-singleton) Use PascalCase when you export a constructor / class / singleton / function library / bare object. ```javascript - function Jedi(options) { - options || (options = {}); - var lightsaber = options.lightsaber || 'blue'; - this.set('lightsaber', lightsaber); - } - - Jedi.prototype.set = function(key, val) { - this[key] = val; + const AirbnbStyleGuide = { + es6: { + }, }; - Jedi.prototype.get = function(key) { - return this[key]; - }; + export default AirbnbStyleGuide; ``` - **[[⬆]](#TOC)** + + - [23.9](#naming--Acronyms-and-Initialisms) Acronyms and initialisms should always be all uppercased, or all lowercased. - -## Constructors - - - Assign methods to the prototype object, instead of overwriting the prototype with a new object. Overwriting the prototype makes inheritance impossible: by resetting the prototype you'll overwrite the base! + > Why? Names are for readability, not to appease a computer algorithm. ```javascript - function Jedi() { - console.log('new jedi'); - } + // bad + import SmsContainer from './containers/SmsContainer'; // bad - Jedi.prototype = { - fight: function fight() { - console.log('fighting'); - }, + const HttpRequests = [ + // ... + ]; - block: function block() { - console.log('blocking'); - } - }; + // good + import SMSContainer from './containers/SMSContainer'; // good - Jedi.prototype.fight = function fight() { - console.log('fighting'); - }; + const HTTPRequests = [ + // ... + ]; - Jedi.prototype.block = function block() { - console.log('blocking'); - }; - ``` + // also good + const httpRequests = [ + // ... + ]; - - Methods can return `this` to help with method chaining. + // best + import TextMessageContainer from './containers/TextMessageContainer'; - ```javascript - // bad - Jedi.prototype.jump = function() { - this.jumping = true; - return true; - }; + // best + const requests = [ + // ... + ]; + ``` - Jedi.prototype.setHeight = function(height) { - this.height = height; - }; + + - [23.10](#naming--uppercase) You may optionally uppercase a constant only if it (1) is exported, (2) is a `const` (it can not be reassigned), and (3) the programmer can trust it (and its nested properties) to never change. - var luke = new Jedi(); - luke.jump(); // => true - luke.setHeight(20) // => undefined + > Why? This is an additional tool to assist in situations where the programmer would be unsure if a variable might ever change. UPPERCASE_VARIABLES are letting the programmer know that they can trust the variable (and its properties) not to change. + - What about all `const` variables? - This is unnecessary, so uppercasing should not be used for constants within a file. It should be used for exported constants however. + - What about exported objects? - Uppercase at the top level of export (e.g. `EXPORTED_OBJECT.key`) and maintain that all nested properties do not change. - // good - Jedi.prototype.jump = function() { - this.jumping = true; - return this; - }; + ```javascript + // bad + const PRIVATE_VARIABLE = 'should not be unnecessarily uppercased within a file'; - Jedi.prototype.setHeight = function(height) { - this.height = height; - return this; - }; + // bad + export const THING_TO_BE_CHANGED = 'should obviously not be uppercased'; - var luke = new Jedi(); + // bad + export let REASSIGNABLE_VARIABLE = 'do not use let with uppercase variables'; - luke.jump() - .setHeight(20); - ``` + // --- + // allowed but does not supply semantic value + export const apiKey = 'SOMEKEY'; - - It's okay to write a custom toString() method, just make sure it works successfully and causes no side effects. + // better in most cases + export const API_KEY = 'SOMEKEY'; - ```javascript - function Jedi(options) { - options || (options = {}); - this.name = options.name || 'no name'; - } + // --- - Jedi.prototype.getName = function getName() { - return this.name; + // bad - unnecessarily uppercases key while adding no semantic value + export const MAPPING = { + KEY: 'value' }; - Jedi.prototype.toString = function toString() { - return 'Jedi - ' + this.getName(); + // good + export const MAPPING = { + key: 'value', }; ``` - **[[⬆]](#TOC)** +**[⬆ back to top](#table-of-contents)** +## Accessors -## Events + + - [24.1](#accessors--not-required) Accessor functions for properties are not required. - - When attaching data payloads to events (whether DOM events or something more proprietary like Backbone events), pass a hash instead of a raw value. This allows a subsequent contributor to add more data to the event payload without finding and updating every handler for the event. For example, instead of: + + - [24.2](#accessors--no-getters-setters) Do not use JavaScript getters/setters as they cause unexpected side effects and are harder to test, maintain, and reason about. Instead, if you do make accessor functions, use `getVal()` and `setVal('hello')`. - ```js + ```javascript // bad - $(this).trigger('listingUpdated', listing.id); + class Dragon { + get age() { + // ... + } + + set age(value) { + // ... + } + } - ... + // good + class Dragon { + getAge() { + // ... + } - $(this).on('listingUpdated', function(e, listingId) { - // do something with listingId - }); + setAge(value) { + // ... + } + } ``` - prefer: + + - [24.3](#accessors--boolean-prefix) If the property/method is a `boolean`, use `isVal()` or `hasVal()`. + + ```javascript + // bad + if (!dragon.age()) { + return false; + } - ```js // good - $(this).trigger('listingUpdated', { listingId : listing.id }); + if (!dragon.hasAge()) { + return false; + } + ``` - ... + + - [24.4](#accessors--consistent) It’s okay to create `get()` and `set()` functions, but be consistent. - $(this).on('listingUpdated', function(e, data) { - // do something with data.listingId - }); - ``` + ```javascript + class Jedi { + constructor(options = {}) { + const lightsaber = options.lightsaber || 'blue'; + this.set('lightsaber', lightsaber); + } + + set(key, val) { + this[key] = val; + } - **[[⬆]](#TOC)** + get(key) { + return this[key]; + } + } + ``` +**[⬆ back to top](#table-of-contents)** -## Modules +## Events - - The module should start with a `!`. This ensures that if a malformed module forgets to include a final semicolon there aren't errors in production when the scripts get concatenated. [Explanation](https://github.com/airbnb/javascript/issues/44#issuecomment-13063933) - - The file should be named with camelCase, live in a folder with the same name, and match the name of the single export. - - Add a method called noConflict() that sets the exported module to the previous version and returns this one. - - Always declare `'use strict';` at the top of the module. + + - [25.1](#events--hash) When attaching data payloads to events (whether DOM events or something more proprietary like Backbone events), pass an object literal (also known as a "hash") instead of a raw value. This allows a subsequent contributor to add more data to the event payload without finding and updating every handler for the event. For example, instead of: ```javascript - // fancyInput/fancyInput.js + // bad + $(this).trigger('listingUpdated', listing.id); - !function(global) { - 'use strict'; + // ... - var previousFancyInput = global.FancyInput; + $(this).on('listingUpdated', (e, listingID) => { + // do something with listingID + }); + ``` - function FancyInput(options) { - this.options = options || {}; - } + prefer: - FancyInput.noConflict = function noConflict() { - global.FancyInput = previousFancyInput; - return FancyInput; - }; + ```javascript + // good + $(this).trigger('listingUpdated', { listingID: listing.id }); - global.FancyInput = FancyInput; - }(this); - ``` + // ... - **[[⬆]](#TOC)** + $(this).on('listingUpdated', (e, data) => { + // do something with data.listingID + }); + ``` + **[⬆ back to top](#table-of-contents)** -## jQuery +## jQuery - - Prefix jQuery object variables with a `$`. + + - [26.1](#jquery--dollar-prefix) Prefix jQuery object variables with a `$`. ```javascript // bad - var sidebar = $('.sidebar'); + const sidebar = $('.sidebar'); + + // good + const $sidebar = $('.sidebar'); // good - var $sidebar = $('.sidebar'); + const $sidebarBtn = $('.sidebar-btn'); ``` - - Cache jQuery lookups. + + - [26.2](#jquery--cache) Cache jQuery lookups. ```javascript // bad function setSidebar() { $('.sidebar').hide(); - // ...stuff... + // ... $('.sidebar').css({ - 'background-color': 'pink' + 'background-color': 'pink', }); } // good function setSidebar() { - var $sidebar = $('.sidebar'); + const $sidebar = $('.sidebar'); $sidebar.hide(); - // ...stuff... + // ... $sidebar.css({ - 'background-color': 'pink' + 'background-color': 'pink', }); } ``` - - For DOM queries use Cascading `$('.sidebar ul')` or parent > child `$('.sidebar > ul')`. [jsPerf](http://jsperf.com/jquery-find-vs-context-sel/16) - - Use `find` with scoped jQuery object queries. + + - [26.3](#jquery--queries) For DOM queries use Cascading `$('.sidebar ul')` or parent > child `$('.sidebar > ul')`. [jsPerf](https://web.archive.org/web/20200414183810/https://jsperf.com/jquery-find-vs-context-sel/16) + + + - [26.4](#jquery--find) Use `find` with scoped jQuery object queries. ```javascript // bad @@ -1371,155 +3741,333 @@ $sidebar.find('ul').hide(); ``` - **[[⬆]](#TOC)** +**[⬆ back to top](#table-of-contents)** + +## ECMAScript 5 Compatibility + + + - [27.1](#es5-compat--kangax) Refer to [Kangax](https://twitter.com/kangax/)’s ES5 [compatibility table](https://compat-table.github.io/compat-table/es5/). + +**[⬆ back to top](#table-of-contents)** + +## ECMAScript 6+ (ES 2015+) Styles -## ECMAScript 5 Compatibility + + - [28.1](#es6-styles) This is a collection of links to the various ES6+ features. - - Refer to [Kangax](https://twitter.com/kangax/)'s ES5 [compatibility table](http://kangax.github.com/es5-compat-table/) +1. [Arrow Functions](#arrow-functions) +1. [Classes](#classes--constructors) +1. [Object Shorthand](#es6-object-shorthand) +1. [Object Concise](#es6-object-concise) +1. [Object Computed Properties](#es6-computed-properties) +1. [Template Strings](#es6-template-literals) +1. [Destructuring](#destructuring) +1. [Default Parameters](#es6-default-parameters) +1. [Rest](#es6-rest) +1. [Array Spreads](#es6-array-spreads) +1. [Let and Const](#references) +1. [Exponentiation Operator](#es2016-properties--exponentiation-operator) +1. [Iterators and Generators](#iterators-and-generators) +1. [Modules](#modules) - **[[⬆]](#TOC)** + + - [28.2](#tc39-proposals) Do not use [TC39 proposals](https://github.com/tc39/proposals) that have not reached stage 3. + > Why? [They are not finalized](https://tc39.github.io/process-document/), and they are subject to change or to be withdrawn entirely. We want to use JavaScript, and proposals are not JavaScript yet. -## Testing +**[⬆ back to top](#table-of-contents)** - - **Yup.** +## Standard Library + + The [Standard Library](https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects) + contains utilities that are functionally broken but remain for legacy reasons. + + + - [29.1](#standard-library--isnan) Use `Number.isNaN` instead of global `isNaN`. + eslint: [`no-restricted-globals`](https://eslint.org/docs/rules/no-restricted-globals) + + > Why? The global `isNaN` coerces non-numbers to numbers, returning true for anything that coerces to NaN. + > If this behavior is desired, make it explicit. ```javascript - function() { - return true; - } + // bad + isNaN('1.2'); // false + isNaN('1.2.3'); // true + + // good + Number.isNaN('1.2.3'); // false + Number.isNaN(Number('1.2.3')); // true + ``` + + + - [29.2](#standard-library--isfinite) Use `Number.isFinite` instead of global `isFinite`. + eslint: [`no-restricted-globals`](https://eslint.org/docs/rules/no-restricted-globals) + + > Why? The global `isFinite` coerces non-numbers to numbers, returning true for anything that coerces to a finite number. + > If this behavior is desired, make it explicit. + + ```javascript + // bad + isFinite('2e3'); // true + + // good + Number.isFinite('2e3'); // false + Number.isFinite(parseInt('2e3', 10)); // true ``` - **[[⬆]](#TOC)** +**[⬆ back to top](#table-of-contents)** +## Testing -## Performance + + - [30.1](#testing--yup) **Yup.** - - [On Layout & Web Performance](http://kellegous.com/j/2013/01/26/layout-performance/) - - [String vs Array Concat](http://jsperf.com/string-vs-array-concat/2) - - [Try/Catch Cost In a Loop](http://jsperf.com/try-catch-in-loop-cost) - - [Bang Function](http://jsperf.com/bang-function) - - [jQuery Find vs Context, Selector](http://jsperf.com/jquery-find-vs-context-sel/13) - - [innerHTML vs textContent for script text](http://jsperf.com/innerhtml-vs-textcontent-for-script-text) - - [Long String Concatenation](http://jsperf.com/ya-string-concat) + ```javascript + function foo() { + return true; + } + ``` + + + - [30.2](#testing--for-real) **No, but seriously**: + - Whichever testing framework you use, you should be writing tests! + - Strive to write many small pure functions, and minimize where mutations occur. + - Be cautious about stubs and mocks - they can make your tests more brittle. + - We primarily use [`mocha`](https://www.npmjs.com/package/mocha) and [`jest`](https://www.npmjs.com/package/jest) at Airbnb. [`tape`](https://www.npmjs.com/package/tape) is also used occasionally for small, separate modules. + - 100% test coverage is a good goal to strive for, even if it’s not always practical to reach it. + - Whenever you fix a bug, *write a regression test*. A bug fixed without a regression test is almost certainly going to break again in the future. + +**[⬆ back to top](#table-of-contents)** + +## Performance + + - [On Layout & Web Performance](https://www.kellegous.com/j/2013/01/26/layout-performance/) + - [String vs Array Concat](https://web.archive.org/web/20200414200857/https://jsperf.com/string-vs-array-concat/2) + - [Try/Catch Cost In a Loop](https://web.archive.org/web/20200414190827/https://jsperf.com/try-catch-in-loop-cost/12) + - [Bang Function](https://web.archive.org/web/20200414205426/https://jsperf.com/bang-function) + - [jQuery Find vs Context, Selector](https://web.archive.org/web/20200414200850/https://jsperf.com/jquery-find-vs-context-sel/164) + - [innerHTML vs textContent for script text](https://web.archive.org/web/20200414205428/https://jsperf.com/innerhtml-vs-textcontent-for-script-text) + - [Long String Concatenation](https://web.archive.org/web/20200414203914/https://jsperf.com/ya-string-concat/38) + - [Are JavaScript functions like `map()`, `reduce()`, and `filter()` optimized for traversing arrays?](https://www.quora.com/JavaScript-programming-language-Are-Javascript-functions-like-map-reduce-and-filter-already-optimized-for-traversing-array/answer/Quildreen-Motta) - Loading... - **[[⬆]](#TOC)** +**[⬆ back to top](#table-of-contents)** +## Resources -## Resources +**Learning ES6+** + - [Latest ECMA spec](https://tc39.github.io/ecma262/) + - [ExploringJS](https://exploringjs.com/) + - [ES6 Compatibility Table](https://compat-table.github.io/compat-table/es6/) + - [Comprehensive Overview of ES6 Features](https://web.archive.org/web/20240404212626/http://es6-features.org/) + - [JavaScript Roadmap](https://roadmap.sh/javascript) **Read This** - - [Annotated ECMAScript 5.1](http://es5.github.com/) + - [Standard ECMA-262](https://www.ecma-international.org/ecma-262/6.0/index.html) + +**Tools** -**Other Styleguides** + - Code Style Linters + - [ESlint](https://eslint.org/) - [Airbnb Style .eslintrc](https://github.com/airbnb/javascript/blob/master/linters/.eslintrc) + - [JSHint](https://jshint.com/) - [Airbnb Style .jshintrc](https://github.com/airbnb/javascript/blob/master/linters/.jshintrc) + - Neutrino Preset - [@neutrinojs/airbnb](https://neutrinojs.org/packages/airbnb/) - - [Google JavaScript Style Guide](http://google-styleguide.googlecode.com/svn/trunk/javascriptguide.xml) - - [jQuery Core Style Guidelines](http://docs.jquery.com/JQuery_Core_Style_Guidelines) - - [Principles of Writing Consistent, Idiomatic JavaScript](https://github.com/rwldrn/idiomatic.js/) +**Other Style Guides** + + - [Google JavaScript Style Guide](https://google.github.io/styleguide/jsguide.html) + - [Google JavaScript Style Guide (Old)](https://google.github.io/styleguide/javascriptguide.xml) + - [jQuery Core Style Guidelines](https://contribute.jquery.org/style-guide/js/) + - [Principles of Writing Consistent, Idiomatic JavaScript](https://github.com/rwaldron/idiomatic.js) + - [StandardJS](https://standardjs.com) **Other Styles** - - [Naming this in nested functions](https://gist.github.com/4135065) - Christian Johansen - - [Conditional Callbacks](https://github.com/airbnb/javascript/issues/52) - - [Popular JavaScript Coding Conventions on Github](http://sideeffect.kr/popularconvention/#javascript) + - [Naming this in nested functions](https://gist.github.com/cjohansen/4135065) - Christian Johansen + - [Conditional Callbacks](https://github.com/airbnb/javascript/issues/52) - Ross Allen + - [Popular JavaScript Coding Conventions on GitHub](http://sideeffect.kr/popularconvention/#javascript) - JeongHoon Byun + - [Multiple var statements in JavaScript, not superfluous](https://benalman.com/news/2012/05/multiple-var-statements-javascript/) - Ben Alman **Further Reading** - - [Understanding JavaScript Closures](http://javascriptweblog.wordpress.com/2010/10/25/understanding-javascript-closures/) - Angus Croll - - [Basic JavaScript for the impatient programmer](http://www.2ality.com/2013/06/basic-javascript.html) - Dr. Axel Rauschmayer - - [You Might Not Need jQuery](http://youmightnotneedjquery.com/) - Zack Bloom & Adam Schwartz + - [Understanding JavaScript Closures](https://javascriptweblog.wordpress.com/2010/10/25/understanding-javascript-closures/) - Angus Croll + - [Basic JavaScript for the impatient programmer](https://www.2ality.com/2013/06/basic-javascript.html) - Dr. Axel Rauschmayer + - [You Might Not Need jQuery](https://youmightnotneedjquery.com/) - Zack Bloom & Adam Schwartz + - [ES6 Features](https://github.com/lukehoban/es6features) - Luke Hoban + - [Frontend Guidelines](https://github.com/bendc/frontend-guidelines) - Benjamin De Cock **Books** - - [JavaScript: The Good Parts](http://www.amazon.com/JavaScript-Good-Parts-Douglas-Crockford/dp/0596517742) - Douglas Crockford - - [JavaScript Patterns](http://www.amazon.com/JavaScript-Patterns-Stoyan-Stefanov/dp/0596806752) - Stoyan Stefanov - - [Pro JavaScript Design Patterns](http://www.amazon.com/JavaScript-Design-Patterns-Recipes-Problem-Solution/dp/159059908X) - Ross Harmes and Dustin Diaz - - [High Performance Web Sites: Essential Knowledge for Front-End Engineers](http://www.amazon.com/High-Performance-Web-Sites-Essential/dp/0596529309) - Steve Souders - - [Maintainable JavaScript](http://www.amazon.com/Maintainable-JavaScript-Nicholas-C-Zakas/dp/1449327680) - Nicholas C. Zakas - - [JavaScript Web Applications](http://www.amazon.com/JavaScript-Web-Applications-Alex-MacCaw/dp/144930351X) - Alex MacCaw - - [Pro JavaScript Techniques](http://www.amazon.com/Pro-JavaScript-Techniques-John-Resig/dp/1590597273) - John Resig - - [Smashing Node.js: JavaScript Everywhere](http://www.amazon.com/Smashing-Node-js-JavaScript-Everywhere-Magazine/dp/1119962595) - Guillermo Rauch - - [Secrets of the JavaScript Ninja](http://www.amazon.com/Secrets-JavaScript-Ninja-John-Resig/dp/193398869X) - John Resig and Bear Bibeault + - [JavaScript: The Good Parts](https://www.amazon.com/JavaScript-Good-Parts-Douglas-Crockford/dp/0596517742) - Douglas Crockford + - [JavaScript Patterns](https://www.amazon.com/JavaScript-Patterns-Stoyan-Stefanov/dp/0596806752) - Stoyan Stefanov + - [Pro JavaScript Design Patterns](https://www.amazon.com/JavaScript-Design-Patterns-Recipes-Problem-Solution/dp/159059908X) - Ross Harmes and Dustin Diaz + - [High Performance Web Sites: Essential Knowledge for Front-End Engineers](https://www.amazon.com/High-Performance-Web-Sites-Essential/dp/0596529309) - Steve Souders + - [Maintainable JavaScript](https://www.amazon.com/Maintainable-JavaScript-Nicholas-C-Zakas/dp/1449327680) - Nicholas C. Zakas + - [JavaScript Web Applications](https://www.amazon.com/JavaScript-Web-Applications-Alex-MacCaw/dp/144930351X) - Alex MacCaw + - [Pro JavaScript Techniques](https://www.amazon.com/Pro-JavaScript-Techniques-John-Resig/dp/1590597273) - John Resig + - [Smashing Node.js: JavaScript Everywhere](https://www.amazon.com/Smashing-Node-js-JavaScript-Everywhere-Magazine/dp/1119962595) - Guillermo Rauch + - [Secrets of the JavaScript Ninja](https://www.amazon.com/Secrets-JavaScript-Ninja-John-Resig/dp/193398869X) - John Resig and Bear Bibeault - [Human JavaScript](http://humanjavascript.com/) - Henrik Joreteg - [Superhero.js](http://superherojs.com/) - Kim Joar Bekkelund, Mads Mobæk, & Olav Bjorkoy - - [JSBooks](http://jsbooks.revolunet.com/) - - [Third Party JavaScript](http://manning.com/vinegar/) - Ben Vinegar and Anton Kovalyov + - [JSBooks](https://jsbooks.revolunet.com/) - Julien Bouquillon + - [Third Party JavaScript](https://www.manning.com/books/third-party-javascript) - Ben Vinegar and Anton Kovalyov + - [Effective JavaScript: 68 Specific Ways to Harness the Power of JavaScript](https://amzn.com/dp/0321812182) - David Herman + - [Eloquent JavaScript](https://eloquentjavascript.net/) - Marijn Haverbeke + - [You Don’t Know JS: ES6 & Beyond](https://shop.oreilly.com/product/0636920033769.do) - Kyle Simpson **Blogs** - - [DailyJS](http://dailyjs.com/) - - [JavaScript Weekly](http://javascriptweekly.com/) - - [JavaScript, JavaScript...](http://javascriptweblog.wordpress.com/) - - [Bocoup Weblog](http://weblog.bocoup.com/) - - [Adequately Good](http://www.adequatelygood.com/) - - [NCZOnline](http://www.nczonline.net/) + - [JavaScript Weekly](https://javascriptweekly.com/) + - [JavaScript, JavaScript...](https://javascriptweblog.wordpress.com/) + - [Bocoup Weblog](https://bocoup.com/weblog) + - [Adequately Good](https://www.adequatelygood.com/) + - [NCZOnline](https://www.nczonline.net/) - [Perfection Kills](http://perfectionkills.com/) - - [Ben Alman](http://benalman.com/) + - [Ben Alman](https://benalman.com/) - [Dmitry Baranovskiy](http://dmitry.baranovskiy.com/) - - [Dustin Diaz](http://dustindiaz.com/) - - [nettuts](http://net.tutsplus.com/?s=javascript) + - [nettuts](https://code.tutsplus.com/?s=javascript) + +**Podcasts** - **[[⬆]](#TOC)** + - [JavaScript Air](https://javascriptair.com/) + - [JavaScript Jabber](https://devchat.tv/js-jabber/) -## In the Wild +**[⬆ back to top](#table-of-contents)** - This is a list of organizations that are using this style guide. Send us a pull request or open an issue and we'll add you to the list. +## In the Wild + This is a list of organizations that are using this style guide. Send us a pull request and we'll add you to the list. + + - **123erfasst**: [123erfasst/javascript](https://github.com/123erfasst/javascript) + - **4Catalyzer**: [4Catalyzer/javascript](https://github.com/4Catalyzer/javascript) - **Aan Zee**: [AanZee/javascript](https://github.com/AanZee/javascript) - **Airbnb**: [airbnb/javascript](https://github.com/airbnb/javascript) - - **American Insitutes for Research**: [AIRAST/javascript](https://github.com/AIRAST/javascript) + - **AloPeyk**: [AloPeyk](https://github.com/AloPeyk) + - **AltSchool**: [AltSchool/javascript](https://github.com/AltSchool/javascript) + - **Apartmint**: [apartmint/javascript](https://github.com/apartmint/javascript) + - **Ascribe**: [ascribe/javascript](https://github.com/ascribe/javascript) + - **Avant**: [avantcredit/javascript](https://github.com/avantcredit/javascript) + - **Axept**: [axept/javascript](https://github.com/axept/javascript) + - **Billabong**: [billabong/javascript](https://github.com/billabong/javascript) + - **Bisk**: [bisk](https://github.com/Bisk/) + - **Brainshark**: [brainshark/javascript](https://github.com/brainshark/javascript) + - **CaseNine**: [CaseNine/javascript](https://github.com/CaseNine/javascript) + - **Cerner**: [Cerner](https://github.com/cerner/) + - **Chartboost**: [ChartBoost/javascript-style-guide](https://github.com/ChartBoost/javascript-style-guide) + - **Coeur d'Alene Tribe**: [www.cdatribe-nsn.gov](https://www.cdatribe-nsn.gov) + - **ComparaOnline**: [comparaonline/javascript](https://github.com/comparaonline/javascript-style-guide) - **Compass Learning**: [compasslearning/javascript-style-guide](https://github.com/compasslearning/javascript-style-guide) + - **DailyMotion**: [dailymotion/javascript](https://github.com/dailymotion/javascript) + - **DoSomething**: [DoSomething/eslint-config](https://github.com/DoSomething/eslint-config) + - **Digitpaint** [digitpaint/javascript](https://github.com/digitpaint/javascript) + - **Drupal**: [www.drupal.org](https://git.drupalcode.org/project/drupal/blob/8.6.x/core/.eslintrc.json) + - **Ecosia**: [ecosia/javascript](https://github.com/ecosia/javascript) + - **Evolution Gaming**: [evolution-gaming/javascript](https://github.com/evolution-gaming/javascript) + - **EvozonJs**: [evozonjs/javascript](https://github.com/evozonjs/javascript) - **ExactTarget**: [ExactTarget/javascript](https://github.com/ExactTarget/javascript) - - **Gawker Media**: [gawkermedia/javascript](https://github.com/gawkermedia/javascript) - - **GeneralElectric**: [GeneralElectric/javascript](https://github.com/GeneralElectric/javascript) + - **Flexberry**: [Flexberry/javascript-style-guide](https://github.com/Flexberry/javascript-style-guide) + - **Gawker Media**: [gawkermedia](https://github.com/gawkermedia/) + - **General Electric**: [GeneralElectric/javascript](https://github.com/GeneralElectric/javascript) + - **Generation Tux**: [GenerationTux/javascript](https://github.com/generationtux/styleguide) - **GoodData**: [gooddata/gdc-js-style](https://github.com/gooddata/gdc-js-style) + - **GreenChef**: [greenchef/javascript](https://github.com/greenchef/javascript) - **Grooveshark**: [grooveshark/javascript](https://github.com/grooveshark/javascript) - - **How About We**: [howaboutwe/javascript](https://github.com/howaboutwe/javascript) + - **Grupo-Abraxas**: [Grupo-Abraxas/javascript](https://github.com/Grupo-Abraxas/javascript) + - **Happeo**: [happeo/javascript](https://github.com/happeo/javascript) + - **How About We**: [howaboutwe/javascript](https://github.com/howaboutwe/javascript-style-guide) + - **HubSpot**: [HubSpot/javascript](https://github.com/HubSpot/javascript) + - **Hyper**: [hyperoslo/javascript-playbook](https://github.com/hyperoslo/javascript-playbook/blob/master/style.md) + - **ILIAS**: [ILIAS](https://github.com/ILIAS-eLearning/ILIAS) + - **InterCity Group**: [intercitygroup/javascript-style-guide](https://github.com/intercitygroup/javascript-style-guide) + - **Jam3**: [Jam3/Javascript-Code-Conventions](https://github.com/Jam3/Javascript-Code-Conventions) + - **JSSolutions**: [JSSolutions/javascript](https://github.com/JSSolutions/javascript) + - **Kaplan Komputing**: [kaplankomputing/javascript](https://github.com/kaplankomputing/javascript) + - **KickorStick**: [kickorstick](https://github.com/kickorstick/) + - **Kinetica Solutions**: [kinetica/javascript](https://github.com/kinetica/Javascript-style-guide) + - **LEINWAND**: [LEINWAND/javascript](https://github.com/LEINWAND/javascript) + - **Lonely Planet**: [lonelyplanet/javascript](https://github.com/lonelyplanet/javascript) + - **M2GEN**: [M2GEN/javascript](https://github.com/M2GEN/javascript) - **Mighty Spring**: [mightyspring/javascript](https://github.com/mightyspring/javascript) - **MinnPost**: [MinnPost/javascript](https://github.com/MinnPost/javascript) - - **ModCloth**: [modcloth/javascript](https://github.com/modcloth/javascript) - - **National Geographic**: [natgeo/javascript](https://github.com/natgeo/javascript) - - **National Park Service**: [nationalparkservice/javascript](https://github.com/nationalparkservice/javascript) + - **MitocGroup**: [MitocGroup/javascript](https://github.com/MitocGroup/javascript) + - **Muber**: [muber](https://github.com/muber/) + - **National Geographic Society**: [natgeosociety](https://github.com/natgeosociety/) + - **NullDev**: [NullDevCo/JavaScript-Styleguide](https://github.com/NullDevCo/JavaScript-Styleguide) + - **Nulogy**: [nulogy/javascript](https://github.com/nulogy/javascript) + - **Orange Hill Development**: [orangehill/javascript](https://github.com/orangehill/javascript) + - **Orion Health**: [orionhealth/javascript](https://github.com/orionhealth/javascript) - **Peerby**: [Peerby/javascript](https://github.com/Peerby/javascript) - - **Razorfish**: [razorfish/javascript-style-guide](https://github.com/razorfish/javascript-style-guide) - - **REI**: [reidev/js-style-guide](https://github.com/reidev/js-style-guide) + - **Pier 1**: [Pier1/javascript](https://github.com/pier1/javascript) + - **Qotto**: [Qotto/javascript-style-guide](https://github.com/Qotto/javascript-style-guide) + - **React**: [reactjs.org/docs/how-to-contribute.html#style-guide](https://reactjs.org/docs/how-to-contribute.html#style-guide) + - **Ripple**: [ripple/javascript-style-guide](https://github.com/ripple/javascript-style-guide) + - **Sainsbury’s Supermarkets**: [jsainsburyplc](https://github.com/jsainsburyplc) - **Shutterfly**: [shutterfly/javascript](https://github.com/shutterfly/javascript) - - **Userify**: [userify/javascript](https://github.com/userify/javascript) + - **Sourcetoad**: [sourcetoad/javascript](https://github.com/sourcetoad/javascript) + - **Springload**: [springload](https://github.com/springload/) + - **StratoDem Analytics**: [stratodem/javascript](https://github.com/stratodem/javascript) + - **SteelKiwi Development**: [steelkiwi/javascript](https://github.com/steelkiwi/javascript) + - **StudentSphere**: [studentsphere/javascript](https://github.com/studentsphere/guide-javascript) + - **SwoopApp**: [swoopapp/javascript](https://github.com/swoopapp/javascript) + - **SysGarage**: [sysgarage/javascript-style-guide](https://github.com/sysgarage/javascript-style-guide) + - **Syzygy Warsaw**: [syzygypl/javascript](https://github.com/syzygypl/javascript) + - **Target**: [target/javascript](https://github.com/target/javascript) + - **Terra**: [terra](https://github.com/cerner?utf8=%E2%9C%93&q=terra&type=&language=) + - **TheLadders**: [TheLadders/javascript](https://github.com/TheLadders/javascript) + - **The Nerdery**: [thenerdery/javascript-standards](https://github.com/thenerdery/javascript-standards) + - **Tomify**: [tomprats](https://github.com/tomprats) + - **Traitify**: [traitify/eslint-config-traitify](https://github.com/traitify/eslint-config-traitify) + - **T4R Technology**: [T4R-Technology/javascript](https://github.com/T4R-Technology/javascript) + - **UrbanSim**: [urbansim](https://github.com/urbansim/) + - **VoxFeed**: [VoxFeed/javascript-style-guide](https://github.com/VoxFeed/javascript-style-guide) + - **WeBox Studio**: [weboxstudio/javascript](https://github.com/weboxstudio/javascript) + - **Weggo**: [Weggo/javascript](https://github.com/Weggo/javascript) - **Zillow**: [zillow/javascript](https://github.com/zillow/javascript) + - **Zit Software**: [zit-software/javascript](https://github.com/zit-software/javascript) - **ZocDoc**: [ZocDoc/javascript](https://github.com/ZocDoc/javascript) -## Translation +**[⬆ back to top](#table-of-contents)** - This style guide is also available in other languages: +## Translation - - :de: **German**: [timofurrer/javascript-style-guide](https://github.com/timofurrer/javascript-style-guide) - - :jp: **Japanese**: [mitsuruog/javacript-style-guide](https://github.com/mitsuruog/javacript-style-guide) - - :br: **Portuguese**: [armoucar/javascript-style-guide](https://github.com/armoucar/javascript-style-guide) - - :cn: **Chinese**: [adamlu/javascript-style-guide](https://github.com/adamlu/javascript-style-guide) - - :es: **Spanish**: [paolocarrasco/javascript-style-guide](https://github.com/paolocarrasco/javascript-style-guide) - - :kr: **Korean**: [tipjs/javascript-style-guide](https://github.com/tipjs/javascript-style-guide) - - :fr: **French**: [nmussy/javascript-style-guide](https://github.com/nmussy/javascript-style-guide) - - :ru: **Russian**: [uprock/javascript](https://github.com/uprock/javascript) - - :bg: **Bulgarian**: [borislavvv/javascript](https://github.com/borislavvv/javascript) + This style guide is also available in other languages: -## The JavaScript Style Guide Guide + - ![br](https://raw.githubusercontent.com/gosquared/flags/master/flags/flags/shiny/24/Brazil.png) **Brazilian Portuguese**: [armoucar/javascript-style-guide](https://github.com/armoucar/javascript-style-guide) + - ![bg](https://raw.githubusercontent.com/gosquared/flags/master/flags/flags/shiny/24/Bulgaria.png) **Bulgarian**: [borislavvv/javascript](https://github.com/borislavvv/javascript) + - ![ca](https://raw.githubusercontent.com/fpmweb/javascript-style-guide/master/img/catala.png) **Catalan**: [fpmweb/javascript-style-guide](https://github.com/fpmweb/javascript-style-guide) + - ![cn](https://raw.githubusercontent.com/gosquared/flags/master/flags/flags/shiny/24/China.png) **Chinese (Simplified)**: [lin-123/javascript](https://github.com/lin-123/javascript) + - ![tw](https://raw.githubusercontent.com/gosquared/flags/master/flags/flags/shiny/24/Taiwan.png) **Chinese (Traditional)**: [jigsawye/javascript](https://github.com/jigsawye/javascript) + - ![fr](https://raw.githubusercontent.com/gosquared/flags/master/flags/flags/shiny/24/France.png) **French**: [nmussy/javascript-style-guide](https://github.com/nmussy/javascript-style-guide) + - ![de](https://raw.githubusercontent.com/gosquared/flags/master/flags/flags/shiny/24/Germany.png) **German**: [timofurrer/javascript-style-guide](https://github.com/timofurrer/javascript-style-guide) + - ![it](https://raw.githubusercontent.com/gosquared/flags/master/flags/flags/shiny/24/Italy.png) **Italian**: [sinkswim/javascript-style-guide](https://github.com/sinkswim/javascript-style-guide) + - ![jp](https://raw.githubusercontent.com/gosquared/flags/master/flags/flags/shiny/24/Japan.png) **Japanese**: [mitsuruog/javascript-style-guide](https://github.com/mitsuruog/javascript-style-guide) + - ![kr](https://raw.githubusercontent.com/gosquared/flags/master/flags/flags/shiny/24/South-Korea.png) **Korean**: [ParkSB/javascript-style-guide](https://github.com/ParkSB/javascript-style-guide) + - ![ru](https://raw.githubusercontent.com/gosquared/flags/master/flags/flags/shiny/24/Russia.png) **Russian**: [leonidlebedev/javascript-airbnb](https://github.com/leonidlebedev/javascript-airbnb) + - ![es](https://raw.githubusercontent.com/gosquared/flags/master/flags/flags/shiny/24/Spain.png) **Spanish**: [paolocarrasco/javascript-style-guide](https://github.com/paolocarrasco/javascript-style-guide) + - ![th](https://raw.githubusercontent.com/gosquared/flags/master/flags/flags/shiny/24/Thailand.png) **Thai**: [lvarayut/javascript-style-guide](https://github.com/lvarayut/javascript-style-guide) + - ![tr](https://raw.githubusercontent.com/gosquared/flags/master/flags/flags/shiny/24/Turkey.png) **Turkish**: [eraycetinay/javascript](https://github.com/eraycetinay/javascript) + - ![ua](https://raw.githubusercontent.com/gosquared/flags/master/flags/flags/shiny/24/Ukraine.png) **Ukrainian**: [ivanzusko/javascript](https://github.com/ivanzusko/javascript) + - ![vn](https://raw.githubusercontent.com/gosquared/flags/master/flags/flags/shiny/24/Vietnam.png) **Vietnam**: [dangkyokhoang/javascript-style-guide](https://github.com/dangkyokhoang/javascript-style-guide) + +## The JavaScript Style Guide Guide - [Reference](https://github.com/airbnb/javascript/wiki/The-JavaScript-Style-Guide-Guide) -## Contributors +## Chat With Us About JavaScript - - [View Contributors](https://github.com/airbnb/javascript/graphs/contributors) + - Find us on [gitter](https://gitter.im/airbnb/javascript). +## Contributors -## License + - [View Contributors](https://github.com/airbnb/javascript/graphs/contributors) + +## License (The MIT License) -Copyright (c) 2014 Airbnb +Copyright (c) 2012 Airbnb Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the @@ -1540,6 +4088,10 @@ CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. -**[[⬆]](#TOC)** +**[⬆ back to top](#table-of-contents)** + +## Amendments + +We encourage you to fork this guide and change the rules to fit your team’s style guide. Below, you may list some amendments to the style guide. This allows you to periodically update your style guide without having to deal with merge conflicts. # }; diff --git a/css-in-javascript/README.md b/css-in-javascript/README.md new file mode 100644 index 0000000000..2e6ab68a1b --- /dev/null +++ b/css-in-javascript/README.md @@ -0,0 +1,432 @@ +# Airbnb CSS-in-JavaScript Style Guide + +*A mostly reasonable approach to CSS-in-JavaScript* + +## Table of Contents + +1. [Naming](#naming) +1. [Ordering](#ordering) +1. [Nesting](#nesting) +1. [Inline](#inline) +1. [Themes](#themes) + +## Naming + + - Use camelCase for object keys (i.e. "selectors"). + + > Why? We access these keys as properties on the `styles` object in the component, so it is most convenient to use camelCase. + + ```js + // bad + { + 'bermuda-triangle': { + display: 'none', + }, + } + + // good + { + bermudaTriangle: { + display: 'none', + }, + } + ``` + + - Use an underscore for modifiers to other styles. + + > Why? Similar to [BEM](https://getbem.com/introduction/), this naming convention makes it clear that the styles are intended to modify the element preceded by the underscore. Underscores do not need to be quoted, so they are preferred over other characters, such as dashes. + + ```js + // bad + { + bruceBanner: { + color: 'pink', + transition: 'color 10s', + }, + + bruceBannerTheHulk: { + color: 'green', + }, + } + + // good + { + bruceBanner: { + color: 'pink', + transition: 'color 10s', + }, + + bruceBanner_theHulk: { + color: 'green', + }, + } + ``` + + - Use `selectorName_fallback` for sets of fallback styles. + + > Why? Similar to modifiers, keeping the naming consistent helps reveal the relationship of these styles to the styles that override them in more adequate browsers. + + ```js + // bad + { + muscles: { + display: 'flex', + }, + + muscles_sadBears: { + width: '100%', + }, + } + + // good + { + muscles: { + display: 'flex', + }, + + muscles_fallback: { + width: '100%', + }, + } + ``` + + - Use a separate selector for sets of fallback styles. + + > Why? Keeping fallback styles contained in a separate object clarifies their purpose, which improves readability. + + ```js + // bad + { + muscles: { + display: 'flex', + }, + + left: { + flexGrow: 1, + display: 'inline-block', + }, + + right: { + display: 'inline-block', + }, + } + + // good + { + muscles: { + display: 'flex', + }, + + left: { + flexGrow: 1, + }, + + left_fallback: { + display: 'inline-block', + }, + + right_fallback: { + display: 'inline-block', + }, + } + ``` + + - Use device-agnostic names (e.g. "small", "medium", and "large") to name media query breakpoints. + + > Why? Commonly used names like "phone", "tablet", and "desktop" do not match the characteristics of the devices in the real world. Using these names sets the wrong expectations. + + ```js + // bad + const breakpoints = { + mobile: '@media (max-width: 639px)', + tablet: '@media (max-width: 1047px)', + desktop: '@media (min-width: 1048px)', + }; + + // good + const breakpoints = { + small: '@media (max-width: 639px)', + medium: '@media (max-width: 1047px)', + large: '@media (min-width: 1048px)', + }; + ``` + +## Ordering + + - Define styles after the component. + + > Why? We use a higher-order component to theme our styles, which is naturally used after the component definition. Passing the styles object directly to this function reduces indirection. + + ```jsx + // bad + const styles = { + container: { + display: 'inline-block', + }, + }; + + function MyComponent({ styles }) { + return ( +
+ Never doubt that a small group of thoughtful, committed citizens can + change the world. Indeed, it’s the only thing that ever has. +
+ ); + } + + export default withStyles(() => styles)(MyComponent); + + // good + function MyComponent({ styles }) { + return ( +
+ Never doubt that a small group of thoughtful, committed citizens can + change the world. Indeed, it’s the only thing that ever has. +
+ ); + } + + export default withStyles(() => ({ + container: { + display: 'inline-block', + }, + }))(MyComponent); + ``` + +## Nesting + + - Leave a blank line between adjacent blocks at the same indentation level. + + > Why? The whitespace improves readability and reduces the likelihood of merge conflicts. + + ```js + // bad + { + bigBang: { + display: 'inline-block', + '::before': { + content: "''", + }, + }, + universe: { + border: 'none', + }, + } + + // good + { + bigBang: { + display: 'inline-block', + + '::before': { + content: "''", + }, + }, + + universe: { + border: 'none', + }, + } + ``` + +## Inline + + - Use inline styles for styles that have a high cardinality (e.g. uses the value of a prop) and not for styles that have a low cardinality. + + > Why? Generating themed stylesheets can be expensive, so they are best for discrete sets of styles. + + ```jsx + // bad + export default function MyComponent({ spacing }) { + return ( +
+ ); + } + + // good + function MyComponent({ styles, spacing }) { + return ( +
+ ); + } + export default withStyles(() => ({ + periodic: { + display: 'table', + }, + }))(MyComponent); + ``` + +## Themes + + - Use an abstraction layer such as [react-with-styles](https://github.com/airbnb/react-with-styles) that enables theming. *react-with-styles gives us things like `withStyles()`, `ThemedStyleSheet`, and `css()` which are used in some of the examples in this document.* + + > Why? It is useful to have a set of shared variables for styling your components. Using an abstraction layer makes this more convenient. Additionally, this can help prevent your components from being tightly coupled to any particular underlying implementation, which gives you more freedom. + + - Define colors only in themes. + + ```js + // bad + export default withStyles(() => ({ + chuckNorris: { + color: '#bada55', + }, + }))(MyComponent); + + // good + export default withStyles(({ color }) => ({ + chuckNorris: { + color: color.badass, + }, + }))(MyComponent); + ``` + + - Define fonts only in themes. + + ```js + // bad + export default withStyles(() => ({ + towerOfPisa: { + fontStyle: 'italic', + }, + }))(MyComponent); + + // good + export default withStyles(({ font }) => ({ + towerOfPisa: { + fontStyle: font.italic, + }, + }))(MyComponent); + ``` + + - Define fonts as sets of related styles. + + ```js + // bad + export default withStyles(() => ({ + towerOfPisa: { + fontFamily: 'Italiana, "Times New Roman", serif', + fontSize: '2em', + fontStyle: 'italic', + lineHeight: 1.5, + }, + }))(MyComponent); + + // good + export default withStyles(({ font }) => ({ + towerOfPisa: { + ...font.italian, + }, + }))(MyComponent); + ``` + + - Define base grid units in theme (either as a value or a function that takes a multiplier). + + ```js + // bad + export default withStyles(() => ({ + rip: { + bottom: '-6912px', // 6 feet + }, + }))(MyComponent); + + // good + export default withStyles(({ units }) => ({ + rip: { + bottom: units(864), // 6 feet, assuming our unit is 8px + }, + }))(MyComponent); + + // good + export default withStyles(({ unit }) => ({ + rip: { + bottom: 864 * unit, // 6 feet, assuming our unit is 8px + }, + }))(MyComponent); + ``` + + - Define media queries only in themes. + + ```js + // bad + export default withStyles(() => ({ + container: { + width: '100%', + + '@media (max-width: 1047px)': { + width: '50%', + }, + }, + }))(MyComponent); + + // good + export default withStyles(({ breakpoint }) => ({ + container: { + width: '100%', + + [breakpoint.medium]: { + width: '50%', + }, + }, + }))(MyComponent); + ``` + + - Define tricky fallback properties in themes. + + > Why? Many CSS-in-JavaScript implementations merge style objects together which makes specifying fallbacks for the same property (e.g. `display`) a little tricky. To keep the approach unified, put these fallbacks in the theme. + + ```js + // bad + export default withStyles(() => ({ + .muscles { + display: 'flex', + }, + + .muscles_fallback { + 'display ': 'table', + }, + }))(MyComponent); + + // good + export default withStyles(({ fallbacks }) => ({ + .muscles { + display: 'flex', + }, + + .muscles_fallback { + [fallbacks.display]: 'table', + }, + }))(MyComponent); + + // good + export default withStyles(({ fallback }) => ({ + .muscles { + display: 'flex', + }, + + .muscles_fallback { + [fallback('display')]: 'table', + }, + }))(MyComponent); + ``` + + - Create as few custom themes as possible. Many applications may only have one theme. + + - Namespace custom theme settings under a nested object with a unique and descriptive key. + + ```js + // bad + ThemedStyleSheet.registerTheme('mySection', { + mySectionPrimaryColor: 'green', + }); + + // good + ThemedStyleSheet.registerTheme('mySection', { + mySection: { + primaryColor: 'green', + }, + }); + ``` + +--- + +CSS puns adapted from [Saijo George](https://saijogeorge.com/css-puns/). diff --git a/linters/.eslintrc b/linters/.eslintrc new file mode 100644 index 0000000000..9e203a5473 --- /dev/null +++ b/linters/.eslintrc @@ -0,0 +1,5 @@ +// Use this file as a starting point for your project's .eslintrc. +// Copy this file, and add rule overrides as needed. +{ + "extends": "airbnb" +} diff --git a/linters/jshintrc b/linters/.jshintrc similarity index 84% rename from linters/jshintrc rename to linters/.jshintrc index d3b47148a8..a7a08a349e 100644 --- a/linters/jshintrc +++ b/linters/.jshintrc @@ -13,6 +13,9 @@ // Define globals exposed by Node.js. "node": true, + // Allow ES6. + "esversion": 6, + /* * ENFORCING OPTIONS * ================= @@ -25,23 +28,23 @@ // Prohibit use of == and != in favor of === and !==. "eqeqeq": true, - // Suppress warnings about == null comparisons. - "eqnull": true, - // Enforce tab width of 2 spaces. "indent": 2, // Prohibit use of a variable before it is defined. "latedef": true, + // Enforce line length to 100 characters + "maxlen": 100, + // Require capitalized names for constructor functions. "newcap": true, // Enforce use of single quotation marks for strings. "quotmark": "single", - // Prohibit trailing whitespace. - "trailing": true, + // Enforce placing 'use strict' at the top function scope + "strict": true, // Prohibit use of explicitly undeclared variables. "undef": true, @@ -49,9 +52,11 @@ // Warn when variables are defined but never used. "unused": true, - // Enforce line length to 80 characters - "maxlen": 80, + /* + * RELAXING OPTIONS + * ================= + */ - // Enforce placing 'use strict' at the top function scope - "strict": true + // Suppress warnings about == null comparisons. + "eqnull": true } diff --git a/linters/.markdownlint.json b/linters/.markdownlint.json new file mode 100644 index 0000000000..951337dbc5 --- /dev/null +++ b/linters/.markdownlint.json @@ -0,0 +1,155 @@ +{ + "comment": "Be explicit by listing every available rule. https://github.com/DavidAnson/markdownlint/blob/master/doc/Rules.md", + "comment": "Note that there will be numeric gaps, not every MD number is implemented in markdownlint.", + + "comment": "MD001: Header levels should only increment by one level at a time.", + "header-increment": true, + + "comment": "MD002: First header should be a top level header.", + "first-header-h1": true, + + "comment": "MD003: Header style: start with hashes.", + "header-style": { + "style": "atx" + }, + + "comment": "MD004: Unordered list style", + "ul-style": { + "style": "dash" + }, + + "comment": "MD005: Consistent indentation for list items at the same level.", + "list-indent": true, + + "comment": "MD006: Consider starting bulleted lists at the beginning of the line.", + "ul-start-left": false, + + "comment": "MD007: Unordered list indentation: 2 spaces.", + "ul-indent": { + "indent": 2, + "start_indented": true + }, + + "comment": "MD009: Disallow trailing spaces!", + "no-trailing-spaces": { + "br_spaces": 0, + "comment": "Empty lines inside list items should not be indented.", + "list_item_empty_lines": false + }, + + "comment": "MD010: No hard tabs, not even in code blocks.", + "no-hard-tabs": { + "code_blocks": true + }, + + "comment": "MD011: Prevent reversed link syntax", + "no-reversed-links": true, + + "comment": "MD012: Disallow multiple consecutive blank lines.", + "no-multiple-blanks": { + "maximum": 1 + }, + + "comment": "MD013: Line length", + "line-length": false, + + "comment": "MD014: Disallow use of dollar signs($) before commands without showing output.", + "commands-show-output": true, + + "comment": "MD018: Disallow space after hash on atx style header.", + "no-missing-space-atx": true, + + "comment": "MD019: Disallow multiple spaces after hash on atx style header.", + "no-multiple-space-atx": true, + + "comment": "MD020: No space should be inside hashes on closed atx style header.", + "no-missing-space-closed-atx": true, + + "comment": "MD021: Disallow multiple spaces inside hashes on closed atx style header.", + "no-multiple-space-closed-atx": true, + + "comment": "MD022: Headers should be surrounded by blank lines.", + "comment": "Some headers have preceding HTML anchors. Unfortunate that we have to disable this, as it otherwise catches a real problem that trips up some Markdown renderers", + "blanks-around-headers": false, + + "comment": "MD023: Headers must start at the beginning of the line.", + "header-start-left": true, + + "comment": "MD024: Disallow multiple headers with the same content.", + "no-duplicate-header": true, + + "comment": "MD025: Disallow multiple top level headers in the same document.", + "comment": "Gotta have a matching closing brace at the end.", + "single-h1": false, + + "comment": "MD026: Disallow trailing punctuation in header.", + "comment": "You must have a semicolon after the ending closing brace.", + "no-trailing-punctuation": { + "punctuation" : ".,:!?" + }, + "comment": "MD027: Dissalow multiple spaces after blockquote symbol", + "no-multiple-space-blockquote": true, + + "comment": "MD028: Blank line inside blockquote", + "comment": "Some 'Why?' and 'Why not?' blocks are separated by a blank line", + "no-blanks-blockquote": false, + + "comment": "MD029: Ordered list item prefix", + "ol-prefix": { + "style": "one" + }, + + "comment": "MD030: Spaces after list markers", + "list-marker-space": { + "ul_single": 1, + "ol_single": 1, + "ul_multi": 1, + "ol_multi": 1 + }, + + "comment": "MD031: Fenced code blocks should be surrounded by blank lines", + "blanks-around-fences": true, + + "comment": "MD032: Lists should be surrounded by blank lines", + "comment": "Some lists have preceding HTML anchors. Unfortunate that we have to disable this, as it otherwise catches a real problem that trips up some Markdown renderers", + "blanks-around-lists": false, + + "comment": "MD033: Disallow inline HTML", + "comment": "HTML is needed for explicit anchors", + "no-inline-html": false, + + "comment": "MD034: No bare URLs should be used", + "no-bare-urls": true, + + "comment": "MD035: Horizontal rule style", + "hr-style": { + "style": "consistent" + }, + + "comment": "MD036: Do not use emphasis instead of a header.", + "no-emphasis-as-header": false, + + "comment": "MD037: Disallow spaces inside emphasis markers.", + "no-space-in-emphasis": true, + + "comment": "MD038: Disallow spaces inside code span elements.", + "no-space-in-code": true, + + "comment": "MD039: Disallow spaces inside link text.", + "no-space-in-links": true, + + "comment": "MD040: Fenced code blocks should have a language specified.", + "fenced-code-language": true, + + "comment": "MD041: First line in file should be a top level header.", + "first-line-h1": true, + + "comment": "MD042: No empty links", + "no-empty-links": true, + + "comment": "MD043: Required header structure.", + "required-headers": false, + + "comment": "MD044: Proper names should have the correct capitalization.", + "proper-names": false +} diff --git a/linters/SublimeLinter/SublimeLinter.sublime-settings b/linters/SublimeLinter/SublimeLinter.sublime-settings index 12360f3f1c..7ce44c9821 100644 --- a/linters/SublimeLinter/SublimeLinter.sublime-settings +++ b/linters/SublimeLinter/SublimeLinter.sublime-settings @@ -9,7 +9,7 @@ * * @version 0.3.0 * @see https://github.com/SublimeLinter/SublimeLinter - * @see http://www.jshint.com/docs/ + * @see https://www.jshint.com/docs/ */ { "jshint_options": @@ -63,7 +63,7 @@ // Warn when variables are defined but never used. "unused": true, - + // Enforce line length to 80 characters "maxlen": 80, diff --git a/package.json b/package.json new file mode 100644 index 0000000000..a78bc250d4 --- /dev/null +++ b/package.json @@ -0,0 +1,46 @@ +{ + "name": "airbnb-style", + "version": "2.0.0", + "description": "A mostly reasonable approach to JavaScript.", + "scripts": { + "preinstall": "npm run install:config && npm run install:config:base", + "postinstall": "rm -rf node_modules/markdownlint-cli/node_modules/markdownlint", + "install:config": "cd packages/eslint-config-airbnb && npm prune && npm install", + "install:config:base": "cd packages/eslint-config-airbnb-base && npm prune && npm install", + "lint": "markdownlint --config linters/.markdownlint.json README.md */README.md", + "pretest": "npm run --silent lint", + "test": "npm run --silent test:config && npm run --silent test:config:base", + "test:config": "cd packages/eslint-config-airbnb; npm test", + "test:config:base": "cd packages/eslint-config-airbnb-base; npm test", + "pretravis": "npm run --silent lint", + "travis": "npm run --silent travis:config && npm run --silent travis:config:base", + "travis:config": "cd packages/eslint-config-airbnb; npm run travis", + "travis:config:base": "cd packages/eslint-config-airbnb-base; npm run travis" + }, + "repository": { + "type": "git", + "url": "https://github.com/airbnb/javascript.git" + }, + "keywords": [ + "style guide", + "lint", + "airbnb", + "es6", + "es2015", + "es2016", + "es2017", + "es2018", + "react", + "jsx" + ], + "author": "Harrison Shoff (https://twitter.com/hshoff)", + "license": "MIT", + "bugs": { + "url": "https://github.com/airbnb/javascript/issues" + }, + "homepage": "https://github.com/airbnb/javascript", + "devDependencies": { + "markdownlint": "^0.29.0", + "markdownlint-cli": "^0.35.0" + } +} diff --git a/packages/eslint-config-airbnb-base/.babelrc b/packages/eslint-config-airbnb-base/.babelrc new file mode 100644 index 0000000000..e0aceaae1c --- /dev/null +++ b/packages/eslint-config-airbnb-base/.babelrc @@ -0,0 +1,3 @@ +{ + "presets": ["airbnb"] +} diff --git a/packages/eslint-config-airbnb-base/.editorconfig b/packages/eslint-config-airbnb-base/.editorconfig new file mode 120000 index 0000000000..1b3ce07def --- /dev/null +++ b/packages/eslint-config-airbnb-base/.editorconfig @@ -0,0 +1 @@ +../../.editorconfig \ No newline at end of file diff --git a/packages/eslint-config-airbnb-base/.eslintrc b/packages/eslint-config-airbnb-base/.eslintrc new file mode 100644 index 0000000000..7606a50a46 --- /dev/null +++ b/packages/eslint-config-airbnb-base/.eslintrc @@ -0,0 +1,10 @@ +{ + "extends": "./index.js", + "rules": { + // disable requiring trailing commas because it might be nice to revert to + // being JSON at some point, and I don't want to make big changes now. + "comma-dangle": 0, + + "max-len": 0, + }, +} diff --git a/packages/eslint-config-airbnb-base/.npmrc b/packages/eslint-config-airbnb-base/.npmrc new file mode 120000 index 0000000000..cba44bb384 --- /dev/null +++ b/packages/eslint-config-airbnb-base/.npmrc @@ -0,0 +1 @@ +../../.npmrc \ No newline at end of file diff --git a/packages/eslint-config-airbnb-base/CHANGELOG.md b/packages/eslint-config-airbnb-base/CHANGELOG.md new file mode 100644 index 0000000000..51522a3f4e --- /dev/null +++ b/packages/eslint-config-airbnb-base/CHANGELOG.md @@ -0,0 +1,374 @@ +15.0.0 / 2021-11-08 +================== + - [breaking] drop eslint < 7, add eslint 8 (#2495) + - [breaking] add `exports` + - [patch] Improve `function-paren-newline` with `multiline-arguments` option (#2471) + - [patch] update default value for complexity (#2420) + - [patch] add disabled `no-unsafe-optional-chaining` rule + - [patch] arthmetic -> arithmetic (#2341) + - [patch] fix spelling of "than" (#2333) + - [patch] add `no-nonoctal-decimal-escape` rule + - [patch] `import/no-extraneous-dependencies`: Add .eslintrc.js to devDeps (#2329) + - [guide] Spread operator => Spread syntax (#2423) + - [guide] add references for eslint rules (#2419) + - [Docs] HTTP => HTTPS (#2489) + - [readme] some updates + - [meta] use `prepublishOnly` script for npm 7+ + - [deps] update `eslint-plugin-import`, `eslint-plugin-react`, `object.entries` + - [dev deps] update `@babel/runtime`, `tape` + +14.2.1 / 2020-11-06 +================== + - [base] `no-restricted-globals`: add better messages (#2320) + - [base] add new core eslint rules, set to off + - [deps] update `confusing-browser-globals`, `object.assign` + - [deps] update `eslint-plugin-import`, use valid `import/no-cycle` `maxDepth` option (#2250, #2249) + - [dev deps] update `@babel/runtime`, `eslint-find-rules`, `eslint-plugin-import` + +14.2.0 / 2020-06-10 +================== + - [new] add `eslint` `v7` + - [minor] Disallow multiple empty lines (#2238) + - [minor] Fix typo in no-multiple-empty-lines rule (#2168) + - [patch] Include 'context' exception for `no-param-reassign` (#2230) + - [patch] Allow triple-slash (///) comments (#2197) + - [patch] Disable `prefer-object-spread` for `airbnb-base/legacy` (#2198) + - [deps] update `eslint-plugin-import`, `eslint-plugin-react`, `babel-preset-airbnb`, `eslint-find-rules`, `in-publish`, `tape`, `object.entries` + +14.1.0 / 2020-03-12 +================== + - [minor] add new disabled rules, update eslint + - [minor] enable `import/no-useless-path-segments` for commonjs (#2113) + - [fix] `whitespace`: only set erroring rules to "warn" + - Fix indentation with JSX Fragments (#2157) + - [patch] `import/no-extraneous-dependencies`: Support karma config files (#2121) + - [readme] normalize multiline word according to merriam-webster (#2138) + - [deps] update `eslint`, `eslint-plugin-import`, `eslint-plugin-react`, `object.entries`, `confusing-browser-globals` + - [dev deps] update `@babel/runtime`, `babel-preset-airbnb`, `safe-publish-latest`, `tape` + - [tests] re-enable eslint rule `prefer-destructuring` internally (#2110) + +14.0.0 / 2019-08-09 +================== + - [breaking] `no-self-assign`: enable `props` option + - [breaking] enable `no-useless-catch` + - [breaking] enable `max-classes-per-file` + - [breaking] enable `no-misleading-character-class` + - [breaking] enable `no-async-promise-executor` + - [breaking] enable `prefer-object-spread` + - [breaking] `func-name-matching`: enable `considerPropertyDescriptor` option + - [breaking] `padded-blocks`: enable `allowSingleLineBlocks` option (#1255) + - [breaking] `no-multiple-empty-lines`: Restrict empty lines at beginning of file (#2042) + - [breaking] Set 'strict' to 'never' (#1962) + - [breaking] legacy: Enable 'strict' (#1962) + - [breaking] Simplifies `no-mixed-operators` (#1864) + - [breaking] Require parens for arrow function args (#1863) + - [breaking] add eslint v6, drop eslint v4 + - [patch] `camelcase`: enable ignoreDestructuring + - [patch] Add markers to spaced-comment block for Flow types (#1966) + - [patch] Do not prefer destructuring for object assignment expression (#1583) + - [deps] update `confusing-browser-globals`, `eslint-plugin-import`, `tape`, `babel-preset-airbnb` + - [dev deps] update babel-related deps to latest + - [dev deps] update `eslint-find-rules`, `eslint-plugin-import` + - [tests] only run tests in non-lint per-package travis job + - [tests] use `eclint` instead of `editorconfig-tools` + +13.2.0 / 2019-07-01 +================== + - [minor] Enforce dangling underscores in method names (#1907) + - [fix] disable `no-var` in legacy entry point + - [patch] Ignore property modifications of `staticContext` params (#2029) + - [patch] `no-extraneous-dependencies`: Add jest.setup.js to devDeps (#1998) + - [meta] add disabled `prefer-named-capture-group` rule + - [meta] add disabled `no-useless-catch` config + - [deps] Switch to confusing-browser-globals (#1961) + - [deps] update `object.entries`, `eslint-plugin-import`, `eslint-plugin-jsx-a11y`, `eslint-plugin-react`, `tape` + - [docs] correct JavaScript capitalization (#2046) + - [readme] Improve eslint config setup instructions for yarn (#2001) + - [docs] fix docs for whitespace config (#1914, #1871) + +13.1.0 / 2018-08-13 +================== + - [new] add eslint v5 support (#1834) + - [deps] update `eslint-plugin-import`, `eslint`, `babel-preset-airbnb`, `safe-publish-latest`, `eslint-find-rules` + - [docs] fix typo in readme (#1855) + - [new] update base ecmaVersion to 2018; remove deprecated experimentalObjectRestSpread option + +13.0.0 / 2018-06-21 +================== + - [breaking] order of import statements is ignored for unassigned imports (#1782) + - [breaking] enable `import/no-cycle`: warn on cyclical dependencies (#1779) + - [breaking] Change import/no-self-import from "off" to "error" (#1770) + - [breaking] Update `object-curly-newline` to match eslint 4.18.0 (#1761) + - [breaking] enable `no-useless-path-segments` (#1743) + - [breaking] Prevent line breaks before and after `=` (#1710) + - [breaking] Add .mjs extension support (#1634) + - [breaking] enable `implicit-arrow-linebreak` + - [breaking] Enables `nonblock-statement-body-position` rule and adds link to guide (#1618) + - [breaking] `no-mixed-operators`: only warn on `**` and `%` mixed with arithmetic operators; removes violation against mixing common math operators. (#1611) + - [breaking] `import/named`: enable + - [breaking] `lines-between-class-members`: set to “always” + - [breaking] `no-else-return`: disallow else-if (#1595) + - [breaking] Enables eslint rule for operator-linebreak + - [new] Adds config entry point with only whitespace rules enabled (#1749, #1751) + - [minor] only allow one newline at the end (#1794) + - [patch] Adjust imports for vue-cli (#1809) + - [patch] Allow devDependencies for `foo_spec.js` naming style (#1732) + - [patch] `function-paren-newline`: change to "consistent" + - [patch] avoid `__mocks__` `no-extraneous-dependencies` check (#1772) + - [patch] Include 'accumulator' exception for `no-param-reassign` (#1768) + - [patch] Set import/extensions to ignorePackages (#1652) + - [patch] properly ignore indentation on jsx + - [patch] `array-callback-return`: enable `allowImplicit` option (#1668) + - [deps] update `eslint`, `eslint-plugin-import` + - [dev deps] update `babel-preset-airbnb`, `tape`, `eslint-find-rules` + - [meta] add ES2015-2018 in npm package keywords (#1587) + - [meta] Add licenses to sub packages (#1746) + - [docs] add `npx` shortcut (#1694) + - [docs] Use HTTPS for links to ESLint documentation (#1628) + - [tests] ensure all entry points parse + +12.1.0 / 2017-10-16 +================== + - [deps] update `eslint` to `v4.9` + +12.0.2 / 2017-10-05 +================== + - [deps] update `eslint` + +12.0.1 / 2017-09-27 +================== + - [fix] ensure all JSX elements are ignored by `indent` (#1569) + - [deps] update `eslint` + +12.0.0 / 2017-09-02 +================== + - [deps] [breaking] require `eslint` v4 + - enable `function-paren-newline`, `for-direction`, `getter-return`, `no-compare-neg-zero`, `semi-style`, `object-curly-newline`, `no-buffer-constructor`, `no-restricted-globals`, `switch-colon-spacing`, `template-tag-spacing`, `prefer-promise-reject-errors`, `prefer-destructuring` + - improve `indent`, `no-multi-spaces`, `no-trailing-spaces`, `no-underscore-dangle` + - [breaking] move `comma-dangle` to Stylistic Issues (#1514) + - [breaking] Rules prohibiting global isNaN, isFinite (#1477) + - [patch] also disallow padding in classes and switches (#1403) + - [patch] support Protractor config files in import/no-extraneous-dependencies (#1543) + +11.3.2 / 2017-08-22 +================== + - [patch] Add jest.config.js to import/no-extraneous-dependencies devDeps (#1522) + - [patch] Improve Gruntfile glob pattern (#1503) + - [deps] update `eslint` v4, `tape` + - [docs] Specify yarn-specific install instructions (#1511) + +11.3.1 / 2017-07-24 +================== + - [fix] `legacy`: remove top-level `ecmaFeatures` + +11.3.0 / 2017-07-23 +================== + - [deps] allow eslint v3 or v4 (#1447) + - [deps] update `eslint-plugin-import` + - [minor] Balanced spacing for inline block comments (#1440) + - [minor] `no-return-assign`: strengthen linting against returning assignments + - [patch] Allow jsx extensions for test files (#1427) + - [patch] `no-restricted-globals`: add confusing globals; leave disabled for now (#1420) + - [patch] Support Protractor config files in import/no-extraneous-dependencies (#1456) + - [docs] Remove TODO in prefer-reflect as it's deprecated (#1452) + - [docs] add yarn instructions (#1463, #1464) + +11.2.0 / 2017-05-14 +================== + - [minor] Disallow unused global variables + +11.1.3 / 2017-04-03 +================== + - [patch] add error messages to `no-restricted-syntax` (#1353) + - [deps] update `eslint` + +11.1.2 / 2017-03-25 +================== + - [patch] `no-param-reassign`: add ignorePropertyModificationsFor (#1325) + - [deps] update `eslint` + +11.1.1 / 2017-03-03 +================== + - [deps] update `eslint` + - [patch] enable `ignoreRestSiblings` in `no-unused-vars` + +11.1.0 / 2017-01-08 +================== + - [minor] enable `no-multi-assign` + - [deps] update `eslint`, `babel-preset-airbnb` + - Update a deprecated option (`eqeqeq`) (#1244) + +11.0.1 / 2017-01-08 +================== + - [deps] update `eslint` + - [docs] add note about `install-peerdeps` (#1234) + - [docs] Updated instructions to support non-bash users (#1214) + +11.0.0 / 2016-12-11 +================== + - [breaking] enable `no-await-in-loop` + - [patch] disable `no-duplicate-imports` rule (#1188, #1195, #1054) + - [patch] `import/no-extraneous-dependencies`: add some comments to ignore patterns + - [patch] add `import/no-extraneous-dependencies` ignore patterns for test files (#1174) + - [patch] `import/no-extraneous-dependencies`: added ignore patterns for config files (#1168) + - [deps] update `eslint`, `eslint-plugin-import`, `tape` + +10.0.1 / 2016-11-07 +================== + - [fix] legacy config should not require `**` + +10.0.0 / 2016-11-06 +================== + - [breaking] prefer `**` over `Math.pow` + - [breaking] `comma-dangle`: require trailing commas for functions + - [breaking] enable `no-useless-return` + - [breaking] tighten up `indent` + - [breaking] tighten up `spaced-comment` + - [breaking] enable `import/no-named-default` + - [patch] loosen `max-len` with `ignoreRegExpLiterals` option + - [patch] loosen `no-extraneous-dependencies` for test files (#959, #1089) + - [deps] update `eslint`, `eslint-plugin-import` + - [dev deps] update `eslint-find-rules` + - [Tests] on `node` `v7` + +9.0.0 / 2016-10-16 +================== + - [breaking] Add `ForOfStatement` to `no-restricted-syntax` (#1122, #1134) + - [breaking] enable `import/no-webpack-loader-syntax` (#1123) + - [breaking] [deps] update `eslint` to `v3.8.0` (#1132) + - [breaking] [deps] update `eslint-plugin-import` to v2 (#1101) + - [patch] `new-cap`: add immutable.js exceptions + - [docs] ensure latest version of config is installed + - [dev deps] update `babel-preset-airbnb`, `eslint`, `eslint-find-rules`, `tape`, `safe-publish-latest` + +8.0.0 / 2016-09-24 +================== + - [breaking] enable rules: `no-restricted-properties`, `prefer-numeric-literals`, `lines-around-directive`, `import/extensions`, `import/no-absolute-path`, `import/no-dynamic-require` + +7.2.0 / 2016-09-23 +================== + - [new] set `ecmaVersion` to 2017; enable object rest/spread; update `babel-preset-airbnb` + - [patch] fix category of `no-restricted-properties` + - [deps] update `eslint`, `eslint-plugin-import`, `eslint-find-rules`, `safe-publish-latest` + +7.1.0 / 2016-09-11 +================== + - [minor] enable `arrow-parens` rule + +7.0.1 / 2016-09-10 +================== + - [patch] loosen `max-len` by ignoring strings + - [deps] update to `eslint` `v3.5.0` + +7.0.0 / 2016-09-06 +================== + - [breaking] Add no-plusplus in style.js and added explanation in README (#1012) + +6.0.0 / 2016-09-06 +================== + - [breaking] `valid-typeof`: enable `requireStringLiterals` option + - [breaking] enable `class-methods-use-this` + - [breaking] enable `symbol-description` + - [breaking] enable `no-bitwise` + - [breaking] enable `no-tabs` + - [breaking] enable `func-call-spacing` + - [breaking] enable `no-template-curly-in-string` + - [patch] remove redundant `DebuggerStatement` from `no-restricted-syntax` (#1031) + - [deps] update `eslint`, `eslint-find-rules`, `eslint-plugin-import` + - Update `ecmaVersion` to `2016` + +5.0.3 / 2016-08-21 +================== + - [fix] correct `import/extensions` list (#1013) + - [refactor] Changed ESLint rule configs to use 'off', 'warn', and 'error' instead of numbers for better readability (#946) + - [deps] update `eslint`, `eslint-plugin-react` + +5.0.2 / 2016-08-12 +================== + - [deps] update `eslint`, `eslint-find-rules`, `eslint-plugin-import` + - [tests] add `safe-publish-latest` to `prepublish` + +5.0.1 / 2016-07-29 +================== + - [patch] `no-unused-expressions`: flesh out options + - [deps] update `eslint` to `v3.2`, `eslint-plugin-import` to `v1.12` + - [tests] improve prepublish script + +5.0.0 / 2016-07-24 +================== + - [breaking] enable `import/newline-after-import` + - [breaking] enable overlooked rules: `linebreak-style`, `new-parens`, `no-continue`, `no-lonely-if`, `operator-assignment`, `space-unary-ops`, `dot-location`, `no-extra-boolean-cast`, `no-this-before-super`, `require-yield`, `no-path-concat`, `no-label-var`, `no-void`, `constructor-super`, `prefer-spread`, `no-new-require`, `no-undef-init`, `no-unexpected-multiline` + - [deps] update `eslint`, `eslint-find-rules`, `eslint-plugin-import`, `babel-tape-runner`; add `babel-preset-airbnb` + - [patch] flesh out defaults: `jsx-quotes` + - [docs] update the peer dep install command to dynamically look up the right version numbers when installing peer deps + - [tests] fix prepublish scripts + +4.0.2 / 2016-07-14 +================== + - [fix] repair accidental comma-dangle change + +4.0.1 / 2016-07-14 (unpublished) +================== + - [fix] Prevent trailing commas in the legacy config (#950) + - [deps] update `eslint-plugin-import` + +4.0.0 / 2016-07-02 +================== + - [breaking] [deps] update `eslint` to v3; drop support for < node 4 + - [breaking] enable `rest-spread-spacing` rule + - [breaking] enable `no-mixed-operators` rule + - [breaking] enable `import` rules: `no-named-as-default`, `no-named-as-default-member`, `no-extraneous-dependencies` + - [breaking] enable `object-property-newline` rule + - [breaking] enable `no-prototype-builtins` rule + - [breaking] enable `no-useless-rename` rule + - [breaking] enable `unicode-bom` rule + - [breaking] Enforce proper generator star spacing (#887) + - [breaking] Enable imports/imports-first rule (#882) + - [breaking] re-order rules; put import rules in separate file (#881) + - [patch] `newline-per-chained-call`: bump the limit to 4 + - [patch] `object-shorthand`: do not warn when the concise form would have a string literal as a name + - [patch] Loosen `prefer-const` to not warn when the variable is “read” before being assigned to + - [refactor] fix quoting of rule properties (#885) + - [refactor] `quotes`: Use object option form rather than deprecated string form. + - [deps] update `eslint`, `eslint-plugin-import`, `eslint-find-rules`, `tape` + - [tests] Only run `eslint-find-rules` on prepublish, not in tests + +3.0.1 / 2016-05-08 +================== + - [patch] re-disable `no-extra-parens` (#869, #867) + +3.0.0 / 2016-05-07 +================== + - [breaking] enable `import/no-mutable-exports` + - [breaking] enable `no-class-assign` rule, to pair with `no-func-assign` + - [breaking] widen `no-extra-parens` to include everything, except `nestedBinaryExpressions` + - [breaking] Re-enabling `newline-per-chained-call` (#748) + - [minor] enable `import/no-amd` + - [patch] enable `import/no-duplicates` + - [deps] update `eslint`, `eslint-plugin-import`, `eslint-find-rules` + +2.0.0 / 2016-04-29 +================== + - [breaking] enable `no-unsafe-finally` rule + - [semver-minor] enable `no-useless-computed-key` rule + - [deps] update `eslint`, `eslint-plugin-import` + +1.0.4 / 2016-04-26 +================== + - [deps] update `eslint-find-rules`, `eslint-plugin-import` + +1.0.3 / 2016-04-21 +================== + - [patch: loosen rules] Allow empty class/object methods + +1.0.2 / 2016-04-20 +================== + - [patch: loosen rules] Allow `break` (#840) + +1.0.1 / 2016-04-19 +================== + - [patch: loosen rules] Allow `== null` (#542) + +1.0.0 / 2016-04-19 +================== + - Initial commmit; moved content over from `eslint-config-airbnb` package. diff --git a/packages/eslint-config-airbnb-base/LICENSE.md b/packages/eslint-config-airbnb-base/LICENSE.md new file mode 100644 index 0000000000..69d80c0252 --- /dev/null +++ b/packages/eslint-config-airbnb-base/LICENSE.md @@ -0,0 +1,21 @@ +MIT License + +Copyright (c) 2012 Airbnb + +Permission is hereby granted, free of charge, to any person obtaining a copy +of this software and associated documentation files (the "Software"), to deal +in the Software without restriction, including without limitation the rights +to use, copy, modify, merge, publish, distribute, sublicense, and/or sell +copies of the Software, and to permit persons to whom the Software is +furnished to do so, subject to the following conditions: + +The above copyright notice and this permission notice shall be included in all +copies or substantial portions of the Software. + +THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR +IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, +FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE +AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER +LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, +OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE +SOFTWARE. diff --git a/packages/eslint-config-airbnb-base/README.md b/packages/eslint-config-airbnb-base/README.md new file mode 100644 index 0000000000..6ddc34dac1 --- /dev/null +++ b/packages/eslint-config-airbnb-base/README.md @@ -0,0 +1,112 @@ +# eslint-config-airbnb-base [![Version Badge][npm-version-svg]][package-url] + +[![npm version](https://badge.fury.io/js/eslint-config-airbnb-base.svg)][package-url] + +[![github actions][actions-image]][actions-url] +[![License][license-image]][license-url] +[![Downloads][downloads-image]][downloads-url] + +This package provides Airbnb's base JS .eslintrc (without React plugins) as an extensible shared config. + +## Usage + +We export two ESLint configurations for your usage. + +### eslint-config-airbnb-base + +Our default export contains all of our ESLint rules, including ECMAScript 6+. It requires `eslint` and `eslint-plugin-import`. + +1. Install the correct versions of each package, which are listed by the command: + + ```sh + npm info "eslint-config-airbnb-base@latest" peerDependencies + ``` + + If using **npm 5+**, use this shortcut + + ```sh + npx install-peerdeps --dev eslint-config-airbnb-base + ``` + + If using **yarn**, you can also use the shortcut described above if you have npm 5+ installed on your machine, as the command will detect that you are using yarn and will act accordingly. + Otherwise, run `npm info "eslint-config-airbnb-base@latest" peerDependencies` to list the peer dependencies and versions, then run `yarn add --dev @` for each listed peer dependency. + + + If using **npm < 5**, Linux/OSX users can run + + ```sh + ( + export PKG=eslint-config-airbnb-base; + npm info "$PKG@latest" peerDependencies --json | command sed 's/[\{\},]//g ; s/: /@/g' | xargs npm install --save-dev "$PKG@latest" + ) + ``` + + Which produces and runs a command like: + + ```sh + npm install --save-dev eslint-config-airbnb-base eslint@^#.#.# eslint-plugin-import@^#.#.# + ``` + + If using **npm < 5**, Windows users can either install all the peer dependencies manually, or use the [install-peerdeps](https://github.com/nathanhleung/install-peerdeps) cli tool. + + ```sh + npm install -g install-peerdeps + install-peerdeps --dev eslint-config-airbnb-base + ``` + + The cli will produce and run a command like: + + ```sh + npm install --save-dev eslint-config-airbnb-base eslint@^#.#.# eslint-plugin-import@^#.#.# + ``` + +2. Add `"extends": "airbnb-base"` to your .eslintrc. + +### eslint-config-airbnb-base/legacy + +Lints ES5 and below. Requires `eslint` and `eslint-plugin-import`. + +1. Install the correct versions of each package, which are listed by the command: + + ```sh + npm info "eslint-config-airbnb-base@latest" peerDependencies + ``` + + Linux/OSX users can run + ```sh + ( + export PKG=eslint-config-airbnb-base; + npm info "$PKG" peerDependencies --json | command sed 's/[\{\},]//g ; s/: /@/g' | xargs npm install --save-dev "$PKG" + ) + ``` + + Which produces and runs a command like: + + ```sh + npm install --save-dev eslint-config-airbnb-base eslint@^#.#.# eslint-plugin-import@^#.#.# + ``` + +2. Add `"extends": "airbnb-base/legacy"` to your .eslintrc + +See [Airbnb's overarching ESLint config](https://npmjs.com/eslint-config-airbnb), [Airbnb's JavaScript styleguide](https://github.com/airbnb/javascript), and the [ESlint config docs](https://eslint.org/docs/user-guide/configuring#extending-configuration-files) for more information. + +### eslint-config-airbnb-base/whitespace + +This entry point only errors on whitespace rules and sets all other rules to warnings. View the list of whitespace rules [here](https://github.com/airbnb/javascript/blob/master/packages/eslint-config-airbnb-base/whitespace.js). + +## Improving this config + +Consider adding test cases if you're making complicated rules changes, like anything involving regexes. Perhaps in a distant future, we could use literate programming to structure our README as test cases for our .eslintrc? + +You can run tests with `npm test`. + +You can make sure this module lints with itself using `npm run lint`. + +[package-url]: https://npmjs.org/package/eslint-config-airbnb-base +[npm-version-svg]: https://versionbadg.es/airbnb/javascript.svg +[license-image]: https://img.shields.io/npm/l/eslint-config-airbnb-base.svg +[license-url]: LICENSE.md +[downloads-image]: https://img.shields.io/npm/dm/eslint-config-airbnb-base.svg +[downloads-url]: https://npm-stat.com/charts.html?package=eslint-config-airbnb-base +[actions-image]: https://img.shields.io/endpoint?url=https://github-actions-badge-u3jn4tfpocch.runkit.sh/airbnb/javascript +[actions-url]: https://github.com/airbnb/javascript/actions diff --git a/packages/eslint-config-airbnb-base/index.js b/packages/eslint-config-airbnb-base/index.js new file mode 100644 index 0000000000..825456b8a4 --- /dev/null +++ b/packages/eslint-config-airbnb-base/index.js @@ -0,0 +1,17 @@ +module.exports = { + extends: [ + './rules/best-practices', + './rules/errors', + './rules/node', + './rules/style', + './rules/variables', + './rules/es6', + './rules/imports', + './rules/strict', + ].map(require.resolve), + parserOptions: { + ecmaVersion: 2018, + sourceType: 'module', + }, + rules: {}, +}; diff --git a/packages/eslint-config-airbnb-base/legacy.js b/packages/eslint-config-airbnb-base/legacy.js new file mode 100644 index 0000000000..e5c9089c75 --- /dev/null +++ b/packages/eslint-config-airbnb-base/legacy.js @@ -0,0 +1,34 @@ +module.exports = { + extends: [ + './rules/best-practices', + './rules/errors', + './rules/node', + './rules/style', + './rules/variables' + ].map(require.resolve), + env: { + browser: true, + node: true, + amd: false, + mocha: false, + jasmine: false + }, + rules: { + 'comma-dangle': ['error', 'never'], + 'prefer-numeric-literals': 'off', + 'no-restricted-properties': ['error', { + object: 'arguments', + property: 'callee', + message: 'arguments.callee is deprecated', + }, { + property: '__defineGetter__', + message: 'Please use Object.defineProperty instead.', + }, { + property: '__defineSetter__', + message: 'Please use Object.defineProperty instead.', + }], + 'no-var': 'off', + 'prefer-object-spread': 'off', + strict: ['error', 'safe'], + } +}; diff --git a/packages/eslint-config-airbnb-base/package.json b/packages/eslint-config-airbnb-base/package.json new file mode 100644 index 0000000000..8f039d4d7c --- /dev/null +++ b/packages/eslint-config-airbnb-base/package.json @@ -0,0 +1,92 @@ +{ + "name": "eslint-config-airbnb-base", + "version": "15.0.0", + "description": "Airbnb's base JS ESLint config, following our styleguide", + "main": "index.js", + "exports": { + ".": "./index.js", + "./legacy": "./legacy.js", + "./whitespace": "./whitespace.js", + "./rules/best-practices": "./rules/best-practices.js", + "./rules/es6": "./rules/es6.js", + "./rules/node": "./rules/node.js", + "./rules/style": "./rules/style.js", + "./rules/errors": "./rules/errors.js", + "./rules/imports": "./rules/imports.js", + "./rules/strict": "./rules/strict.js", + "./rules/variables": "./rules/variables.js", + "./package.json": "./package.json" + }, + "scripts": { + "prelint": "eclint check $(git ls-files | xargs find 2> /dev/null | grep -vE 'node_modules|\\.git')", + "lint": "eslint --report-unused-disable-directives .", + "pretests-only": "node ./test/requires", + "tests-only": "babel-tape-runner ./test/test-*.js", + "prepublishOnly": "eslint-find-rules --unused && npm test && safe-publish-latest", + "prepublish": "not-in-publish || npm run prepublishOnly", + "pretest": "npm run --silent lint", + "test": "npm run --silent tests-only", + "pretravis": ":", + "travis": "npm run --silent tests-only", + "posttravis": ":" + }, + "repository": { + "type": "git", + "url": "https://github.com/airbnb/javascript" + }, + "keywords": [ + "eslint", + "eslintconfig", + "config", + "airbnb", + "javascript", + "styleguide", + "es2015", + "es2016", + "es2017", + "es2018" + ], + "author": "Jake Teton-Landis (https://twitter.com/@jitl)", + "contributors": [ + { + "name": "Jake Teton-Landis", + "url": "https://twitter.com/jitl" + }, + { + "name": "Jordan Harband", + "email": "ljharb@gmail.com", + "url": "http://ljharb.codes" + }, + { + "name": "Harrison Shoff", + "url": "https://twitter.com/hshoff" + } + ], + "license": "MIT", + "bugs": { + "url": "https://github.com/airbnb/javascript/issues" + }, + "homepage": "https://github.com/airbnb/javascript", + "devDependencies": { + "@babel/runtime": "^7.25.6", + "babel-preset-airbnb": "^4.5.0", + "babel-tape-runner": "^3.0.0", + "eclint": "^2.8.1", + "eslint": "^7.32.0 || ^8.2.0", + "eslint-find-rules": "^4.1.0", + "eslint-plugin-import": "^2.30.0", + "in-publish": "^2.0.1", + "safe-publish-latest": "^2.0.0", + "tape": "^5.9.0" + }, + "peerDependencies": { + "eslint": "^7.32.0 || ^8.2.0", + "eslint-plugin-import": "^2.30.0" + }, + "engines": { + "node": "^10.12.0 || >=12.0.0" + }, + "dependencies": { + "confusing-browser-globals": "^1.0.11" + } +} diff --git a/packages/eslint-config-airbnb-base/rules/best-practices.js b/packages/eslint-config-airbnb-base/rules/best-practices.js new file mode 100644 index 0000000000..09c247451a --- /dev/null +++ b/packages/eslint-config-airbnb-base/rules/best-practices.js @@ -0,0 +1,424 @@ +module.exports = { + rules: { + // enforces getter/setter pairs in objects + // https://eslint.org/docs/rules/accessor-pairs + 'accessor-pairs': 'off', + + // enforces return statements in callbacks of array's methods + // https://eslint.org/docs/rules/array-callback-return + 'array-callback-return': ['error', { allowImplicit: true }], + + // treat var statements as if they were block scoped + // https://eslint.org/docs/rules/block-scoped-var + 'block-scoped-var': 'error', + + // specify the maximum cyclomatic complexity allowed in a program + // https://eslint.org/docs/rules/complexity + complexity: ['off', 20], + + // enforce that class methods use "this" + // https://eslint.org/docs/rules/class-methods-use-this + 'class-methods-use-this': ['error', { + exceptMethods: [], + }], + + // require return statements to either always or never specify values + // https://eslint.org/docs/rules/consistent-return + 'consistent-return': 'error', + + // specify curly brace conventions for all control statements + // https://eslint.org/docs/rules/curly + curly: ['error', 'multi-line'], // multiline + + // require default case in switch statements + // https://eslint.org/docs/rules/default-case + 'default-case': ['error', { commentPattern: '^no default$' }], + + // Enforce default clauses in switch statements to be last + // https://eslint.org/docs/rules/default-case-last + 'default-case-last': 'error', + + // https://eslint.org/docs/rules/default-param-last + 'default-param-last': 'error', + + // encourages use of dot notation whenever possible + // https://eslint.org/docs/rules/dot-notation + 'dot-notation': ['error', { allowKeywords: true }], + + // enforces consistent newlines before or after dots + // https://eslint.org/docs/rules/dot-location + 'dot-location': ['error', 'property'], + + // require the use of === and !== + // https://eslint.org/docs/rules/eqeqeq + eqeqeq: ['error', 'always', { null: 'ignore' }], + + // Require grouped accessor pairs in object literals and classes + // https://eslint.org/docs/rules/grouped-accessor-pairs + 'grouped-accessor-pairs': 'error', + + // make sure for-in loops have an if statement + // https://eslint.org/docs/rules/guard-for-in + 'guard-for-in': 'error', + + // enforce a maximum number of classes per file + // https://eslint.org/docs/rules/max-classes-per-file + 'max-classes-per-file': ['error', 1], + + // disallow the use of alert, confirm, and prompt + // https://eslint.org/docs/rules/no-alert + // TODO: enable, semver-major + 'no-alert': 'warn', + + // disallow use of arguments.caller or arguments.callee + // https://eslint.org/docs/rules/no-caller + 'no-caller': 'error', + + // disallow lexical declarations in case/default clauses + // https://eslint.org/docs/rules/no-case-declarations + 'no-case-declarations': 'error', + + // Disallow returning value in constructor + // https://eslint.org/docs/rules/no-constructor-return + 'no-constructor-return': 'error', + + // disallow division operators explicitly at beginning of regular expression + // https://eslint.org/docs/rules/no-div-regex + 'no-div-regex': 'off', + + // disallow else after a return in an if + // https://eslint.org/docs/rules/no-else-return + 'no-else-return': ['error', { allowElseIf: false }], + + // disallow empty functions, except for standalone funcs/arrows + // https://eslint.org/docs/rules/no-empty-function + 'no-empty-function': ['error', { + allow: [ + 'arrowFunctions', + 'functions', + 'methods', + ] + }], + + // disallow empty destructuring patterns + // https://eslint.org/docs/rules/no-empty-pattern + 'no-empty-pattern': 'error', + + // Disallow empty static blocks + // https://eslint.org/docs/latest/rules/no-empty-static-block + // TODO: semver-major, enable + 'no-empty-static-block': 'off', + + // disallow comparisons to null without a type-checking operator + // https://eslint.org/docs/rules/no-eq-null + 'no-eq-null': 'off', + + // disallow use of eval() + // https://eslint.org/docs/rules/no-eval + 'no-eval': 'error', + + // disallow adding to native types + // https://eslint.org/docs/rules/no-extend-native + 'no-extend-native': 'error', + + // disallow unnecessary function binding + // https://eslint.org/docs/rules/no-extra-bind + 'no-extra-bind': 'error', + + // disallow Unnecessary Labels + // https://eslint.org/docs/rules/no-extra-label + 'no-extra-label': 'error', + + // disallow fallthrough of case statements + // https://eslint.org/docs/rules/no-fallthrough + 'no-fallthrough': 'error', + + // disallow the use of leading or trailing decimal points in numeric literals + // https://eslint.org/docs/rules/no-floating-decimal + 'no-floating-decimal': 'error', + + // disallow reassignments of native objects or read-only globals + // https://eslint.org/docs/rules/no-global-assign + 'no-global-assign': ['error', { exceptions: [] }], + + // deprecated in favor of no-global-assign + // https://eslint.org/docs/rules/no-native-reassign + 'no-native-reassign': 'off', + + // disallow implicit type conversions + // https://eslint.org/docs/rules/no-implicit-coercion + 'no-implicit-coercion': ['off', { + boolean: false, + number: true, + string: true, + allow: [], + }], + + // disallow var and named functions in global scope + // https://eslint.org/docs/rules/no-implicit-globals + 'no-implicit-globals': 'off', + + // disallow use of eval()-like methods + // https://eslint.org/docs/rules/no-implied-eval + 'no-implied-eval': 'error', + + // disallow this keywords outside of classes or class-like objects + // https://eslint.org/docs/rules/no-invalid-this + 'no-invalid-this': 'off', + + // disallow usage of __iterator__ property + // https://eslint.org/docs/rules/no-iterator + 'no-iterator': 'error', + + // disallow use of labels for anything other than loops and switches + // https://eslint.org/docs/rules/no-labels + 'no-labels': ['error', { allowLoop: false, allowSwitch: false }], + + // disallow unnecessary nested blocks + // https://eslint.org/docs/rules/no-lone-blocks + 'no-lone-blocks': 'error', + + // disallow creation of functions within loops + // https://eslint.org/docs/rules/no-loop-func + 'no-loop-func': 'error', + + // disallow magic numbers + // https://eslint.org/docs/rules/no-magic-numbers + 'no-magic-numbers': ['off', { + ignore: [], + ignoreArrayIndexes: true, + enforceConst: true, + detectObjects: false, + }], + + // disallow use of multiple spaces + // https://eslint.org/docs/rules/no-multi-spaces + 'no-multi-spaces': ['error', { + ignoreEOLComments: false, + }], + + // disallow use of multiline strings + // https://eslint.org/docs/rules/no-multi-str + 'no-multi-str': 'error', + + // disallow use of new operator when not part of the assignment or comparison + // https://eslint.org/docs/rules/no-new + 'no-new': 'error', + + // disallow use of new operator for Function object + // https://eslint.org/docs/rules/no-new-func + 'no-new-func': 'error', + + // disallows creating new instances of String, Number, and Boolean + // https://eslint.org/docs/rules/no-new-wrappers + 'no-new-wrappers': 'error', + + // Disallow \8 and \9 escape sequences in string literals + // https://eslint.org/docs/rules/no-nonoctal-decimal-escape + 'no-nonoctal-decimal-escape': 'error', + + // Disallow calls to the Object constructor without an argument + // https://eslint.org/docs/latest/rules/no-object-constructor + // TODO: enable, semver-major + 'no-object-constructor': 'off', + + // disallow use of (old style) octal literals + // https://eslint.org/docs/rules/no-octal + 'no-octal': 'error', + + // disallow use of octal escape sequences in string literals, such as + // var foo = 'Copyright \251'; + // https://eslint.org/docs/rules/no-octal-escape + 'no-octal-escape': 'error', + + // disallow reassignment of function parameters + // disallow parameter object manipulation except for specific exclusions + // rule: https://eslint.org/docs/rules/no-param-reassign.html + 'no-param-reassign': ['error', { + props: true, + ignorePropertyModificationsFor: [ + 'acc', // for reduce accumulators + 'accumulator', // for reduce accumulators + 'e', // for e.returnvalue + 'ctx', // for Koa routing + 'context', // for Koa routing + 'req', // for Express requests + 'request', // for Express requests + 'res', // for Express responses + 'response', // for Express responses + '$scope', // for Angular 1 scopes + 'staticContext', // for ReactRouter context + ] + }], + + // disallow usage of __proto__ property + // https://eslint.org/docs/rules/no-proto + 'no-proto': 'error', + + // disallow declaring the same variable more than once + // https://eslint.org/docs/rules/no-redeclare + 'no-redeclare': 'error', + + // disallow certain object properties + // https://eslint.org/docs/rules/no-restricted-properties + 'no-restricted-properties': ['error', { + object: 'arguments', + property: 'callee', + message: 'arguments.callee is deprecated', + }, { + object: 'global', + property: 'isFinite', + message: 'Please use Number.isFinite instead', + }, { + object: 'self', + property: 'isFinite', + message: 'Please use Number.isFinite instead', + }, { + object: 'window', + property: 'isFinite', + message: 'Please use Number.isFinite instead', + }, { + object: 'global', + property: 'isNaN', + message: 'Please use Number.isNaN instead', + }, { + object: 'self', + property: 'isNaN', + message: 'Please use Number.isNaN instead', + }, { + object: 'window', + property: 'isNaN', + message: 'Please use Number.isNaN instead', + }, { + property: '__defineGetter__', + message: 'Please use Object.defineProperty instead.', + }, { + property: '__defineSetter__', + message: 'Please use Object.defineProperty instead.', + }, { + object: 'Math', + property: 'pow', + message: 'Use the exponentiation operator (**) instead.', + }], + + // disallow use of assignment in return statement + // https://eslint.org/docs/rules/no-return-assign + 'no-return-assign': ['error', 'always'], + + // disallow redundant `return await` + // https://eslint.org/docs/rules/no-return-await + 'no-return-await': 'error', + + // disallow use of `javascript:` urls. + // https://eslint.org/docs/rules/no-script-url + 'no-script-url': 'error', + + // disallow self assignment + // https://eslint.org/docs/rules/no-self-assign + 'no-self-assign': ['error', { + props: true, + }], + + // disallow comparisons where both sides are exactly the same + // https://eslint.org/docs/rules/no-self-compare + 'no-self-compare': 'error', + + // disallow use of comma operator + // https://eslint.org/docs/rules/no-sequences + 'no-sequences': 'error', + + // restrict what can be thrown as an exception + // https://eslint.org/docs/rules/no-throw-literal + 'no-throw-literal': 'error', + + // disallow unmodified conditions of loops + // https://eslint.org/docs/rules/no-unmodified-loop-condition + 'no-unmodified-loop-condition': 'off', + + // disallow usage of expressions in statement position + // https://eslint.org/docs/rules/no-unused-expressions + 'no-unused-expressions': ['error', { + allowShortCircuit: false, + allowTernary: false, + allowTaggedTemplates: false, + }], + + // disallow unused labels + // https://eslint.org/docs/rules/no-unused-labels + 'no-unused-labels': 'error', + + // disallow unnecessary .call() and .apply() + // https://eslint.org/docs/rules/no-useless-call + 'no-useless-call': 'off', + + // Disallow unnecessary catch clauses + // https://eslint.org/docs/rules/no-useless-catch + 'no-useless-catch': 'error', + + // disallow useless string concatenation + // https://eslint.org/docs/rules/no-useless-concat + 'no-useless-concat': 'error', + + // disallow unnecessary string escaping + // https://eslint.org/docs/rules/no-useless-escape + 'no-useless-escape': 'error', + + // disallow redundant return; keywords + // https://eslint.org/docs/rules/no-useless-return + 'no-useless-return': 'error', + + // disallow use of void operator + // https://eslint.org/docs/rules/no-void + 'no-void': 'error', + + // disallow usage of configurable warning terms in comments: e.g. todo + // https://eslint.org/docs/rules/no-warning-comments + 'no-warning-comments': ['off', { terms: ['todo', 'fixme', 'xxx'], location: 'start' }], + + // disallow use of the with statement + // https://eslint.org/docs/rules/no-with + 'no-with': 'error', + + // require using Error objects as Promise rejection reasons + // https://eslint.org/docs/rules/prefer-promise-reject-errors + 'prefer-promise-reject-errors': ['error', { allowEmptyReject: true }], + + // Suggest using named capture group in regular expression + // https://eslint.org/docs/rules/prefer-named-capture-group + 'prefer-named-capture-group': 'off', + + // Prefer Object.hasOwn() over Object.prototype.hasOwnProperty.call() + // https://eslint.org/docs/rules/prefer-object-has-own + // TODO: semver-major: enable thus rule, once eslint v8.5.0 is required + 'prefer-object-has-own': 'off', + + // https://eslint.org/docs/rules/prefer-regex-literals + 'prefer-regex-literals': ['error', { + disallowRedundantWrapping: true, + }], + + // require use of the second argument for parseInt() + // https://eslint.org/docs/rules/radix + radix: 'error', + + // require `await` in `async function` (note: this is a horrible rule that should never be used) + // https://eslint.org/docs/rules/require-await + 'require-await': 'off', + + // Enforce the use of u flag on RegExp + // https://eslint.org/docs/rules/require-unicode-regexp + 'require-unicode-regexp': 'off', + + // requires to declare all vars on top of their containing scope + // https://eslint.org/docs/rules/vars-on-top + 'vars-on-top': 'error', + + // require immediate function invocation to be wrapped in parentheses + // https://eslint.org/docs/rules/wrap-iife.html + 'wrap-iife': ['error', 'outside', { functionPrototypeMethods: false }], + + // require or disallow Yoda conditions + // https://eslint.org/docs/rules/yoda + yoda: 'error' + } +}; diff --git a/packages/eslint-config-airbnb-base/rules/errors.js b/packages/eslint-config-airbnb-base/rules/errors.js new file mode 100644 index 0000000000..a3dda4e510 --- /dev/null +++ b/packages/eslint-config-airbnb-base/rules/errors.js @@ -0,0 +1,189 @@ +module.exports = { + rules: { + // Enforce “for” loop update clause moving the counter in the right direction + // https://eslint.org/docs/rules/for-direction + 'for-direction': 'error', + + // Enforces that a return statement is present in property getters + // https://eslint.org/docs/rules/getter-return + 'getter-return': ['error', { allowImplicit: true }], + + // disallow using an async function as a Promise executor + // https://eslint.org/docs/rules/no-async-promise-executor + 'no-async-promise-executor': 'error', + + // Disallow await inside of loops + // https://eslint.org/docs/rules/no-await-in-loop + 'no-await-in-loop': 'error', + + // Disallow comparisons to negative zero + // https://eslint.org/docs/rules/no-compare-neg-zero + 'no-compare-neg-zero': 'error', + + // disallow assignment in conditional expressions + 'no-cond-assign': ['error', 'always'], + + // disallow use of console + 'no-console': 'warn', + + // Disallows expressions where the operation doesn't affect the value + // https://eslint.org/docs/rules/no-constant-binary-expression + // TODO: semver-major, enable + 'no-constant-binary-expression': 'off', + + // disallow use of constant expressions in conditions + 'no-constant-condition': 'warn', + + // disallow control characters in regular expressions + 'no-control-regex': 'error', + + // disallow use of debugger + 'no-debugger': 'error', + + // disallow duplicate arguments in functions + 'no-dupe-args': 'error', + + // Disallow duplicate conditions in if-else-if chains + // https://eslint.org/docs/rules/no-dupe-else-if + 'no-dupe-else-if': 'error', + + // disallow duplicate keys when creating object literals + 'no-dupe-keys': 'error', + + // disallow a duplicate case label. + 'no-duplicate-case': 'error', + + // disallow empty statements + 'no-empty': 'error', + + // disallow the use of empty character classes in regular expressions + 'no-empty-character-class': 'error', + + // disallow assigning to the exception in a catch block + 'no-ex-assign': 'error', + + // disallow double-negation boolean casts in a boolean context + // https://eslint.org/docs/rules/no-extra-boolean-cast + 'no-extra-boolean-cast': 'error', + + // disallow unnecessary parentheses + // https://eslint.org/docs/rules/no-extra-parens + 'no-extra-parens': ['off', 'all', { + conditionalAssign: true, + nestedBinaryExpressions: false, + returnAssign: false, + ignoreJSX: 'all', // delegate to eslint-plugin-react + enforceForArrowConditionals: false, + }], + + // disallow unnecessary semicolons + 'no-extra-semi': 'error', + + // disallow overwriting functions written as function declarations + 'no-func-assign': 'error', + + // https://eslint.org/docs/rules/no-import-assign + 'no-import-assign': 'error', + + // disallow function or variable declarations in nested blocks + 'no-inner-declarations': 'error', + + // disallow invalid regular expression strings in the RegExp constructor + 'no-invalid-regexp': 'error', + + // disallow irregular whitespace outside of strings and comments + 'no-irregular-whitespace': 'error', + + // Disallow Number Literals That Lose Precision + // https://eslint.org/docs/rules/no-loss-of-precision + 'no-loss-of-precision': 'error', + + // Disallow characters which are made with multiple code points in character class syntax + // https://eslint.org/docs/rules/no-misleading-character-class + 'no-misleading-character-class': 'error', + + // disallow the use of object properties of the global object (Math and JSON) as functions + 'no-obj-calls': 'error', + + // Disallow new operators with global non-constructor functions + // https://eslint.org/docs/latest/rules/no-new-native-nonconstructor + // TODO: semver-major, enable + 'no-new-native-nonconstructor': 'off', + + // Disallow returning values from Promise executor functions + // https://eslint.org/docs/rules/no-promise-executor-return + 'no-promise-executor-return': 'error', + + // disallow use of Object.prototypes builtins directly + // https://eslint.org/docs/rules/no-prototype-builtins + 'no-prototype-builtins': 'error', + + // disallow multiple spaces in a regular expression literal + 'no-regex-spaces': 'error', + + // Disallow returning values from setters + // https://eslint.org/docs/rules/no-setter-return + 'no-setter-return': 'error', + + // disallow sparse arrays + 'no-sparse-arrays': 'error', + + // Disallow template literal placeholder syntax in regular strings + // https://eslint.org/docs/rules/no-template-curly-in-string + 'no-template-curly-in-string': 'error', + + // Avoid code that looks like two expressions but is actually one + // https://eslint.org/docs/rules/no-unexpected-multiline + 'no-unexpected-multiline': 'error', + + // disallow unreachable statements after a return, throw, continue, or break statement + 'no-unreachable': 'error', + + // Disallow loops with a body that allows only one iteration + // https://eslint.org/docs/rules/no-unreachable-loop + 'no-unreachable-loop': ['error', { + ignore: [], // WhileStatement, DoWhileStatement, ForStatement, ForInStatement, ForOfStatement + }], + + // disallow return/throw/break/continue inside finally blocks + // https://eslint.org/docs/rules/no-unsafe-finally + 'no-unsafe-finally': 'error', + + // disallow negating the left operand of relational operators + // https://eslint.org/docs/rules/no-unsafe-negation + 'no-unsafe-negation': 'error', + + // disallow use of optional chaining in contexts where the undefined value is not allowed + // https://eslint.org/docs/rules/no-unsafe-optional-chaining + 'no-unsafe-optional-chaining': ['error', { disallowArithmeticOperators: true }], + + // Disallow Unused Private Class Members + // https://eslint.org/docs/rules/no-unused-private-class-members + // TODO: enable once eslint 7 is dropped (which is semver-major) + 'no-unused-private-class-members': 'off', + + // Disallow useless backreferences in regular expressions + // https://eslint.org/docs/rules/no-useless-backreference + 'no-useless-backreference': 'error', + + // disallow negation of the left operand of an in expression + // deprecated in favor of no-unsafe-negation + 'no-negated-in-lhs': 'off', + + // Disallow assignments that can lead to race conditions due to usage of await or yield + // https://eslint.org/docs/rules/require-atomic-updates + // note: not enabled because it is very buggy + 'require-atomic-updates': 'off', + + // disallow comparisons with the value NaN + 'use-isnan': 'error', + + // ensure JSDoc comments are valid + // https://eslint.org/docs/rules/valid-jsdoc + 'valid-jsdoc': 'off', + + // ensure that the results of typeof are compared against a valid string + // https://eslint.org/docs/rules/valid-typeof + 'valid-typeof': ['error', { requireStringLiterals: true }], + } +}; diff --git a/packages/eslint-config-airbnb-base/rules/es6.js b/packages/eslint-config-airbnb-base/rules/es6.js new file mode 100644 index 0000000000..5e59cbebf4 --- /dev/null +++ b/packages/eslint-config-airbnb-base/rules/es6.js @@ -0,0 +1,185 @@ +module.exports = { + env: { + es6: true + }, + parserOptions: { + ecmaVersion: 6, + sourceType: 'module', + ecmaFeatures: { + generators: false, + objectLiteralDuplicateProperties: false + } + }, + + rules: { + // enforces no braces where they can be omitted + // https://eslint.org/docs/rules/arrow-body-style + // TODO: enable requireReturnForObjectLiteral? + 'arrow-body-style': ['error', 'as-needed', { + requireReturnForObjectLiteral: false, + }], + + // require parens in arrow function arguments + // https://eslint.org/docs/rules/arrow-parens + 'arrow-parens': ['error', 'always'], + + // require space before/after arrow function's arrow + // https://eslint.org/docs/rules/arrow-spacing + 'arrow-spacing': ['error', { before: true, after: true }], + + // verify super() callings in constructors + 'constructor-super': 'error', + + // enforce the spacing around the * in generator functions + // https://eslint.org/docs/rules/generator-star-spacing + 'generator-star-spacing': ['error', { before: false, after: true }], + + // disallow modifying variables of class declarations + // https://eslint.org/docs/rules/no-class-assign + 'no-class-assign': 'error', + + // disallow arrow functions where they could be confused with comparisons + // https://eslint.org/docs/rules/no-confusing-arrow + 'no-confusing-arrow': ['error', { + allowParens: true, + }], + + // disallow modifying variables that are declared using const + 'no-const-assign': 'error', + + // disallow duplicate class members + // https://eslint.org/docs/rules/no-dupe-class-members + 'no-dupe-class-members': 'error', + + // disallow importing from the same path more than once + // https://eslint.org/docs/rules/no-duplicate-imports + // replaced by https://github.com/import-js/eslint-plugin-import/blob/master/docs/rules/no-duplicates.md + 'no-duplicate-imports': 'off', + + // disallow symbol constructor + // https://eslint.org/docs/rules/no-new-symbol + 'no-new-symbol': 'error', + + // Disallow specified names in exports + // https://eslint.org/docs/rules/no-restricted-exports + 'no-restricted-exports': ['error', { + restrictedNamedExports: [ + 'default', // use `export default` to provide a default export + 'then', // this will cause tons of confusion when your module is dynamically `import()`ed, and will break in most node ESM versions + ], + }], + + // disallow specific imports + // https://eslint.org/docs/rules/no-restricted-imports + 'no-restricted-imports': ['off', { + paths: [], + patterns: [] + }], + + // disallow to use this/super before super() calling in constructors. + // https://eslint.org/docs/rules/no-this-before-super + 'no-this-before-super': 'error', + + // disallow useless computed property keys + // https://eslint.org/docs/rules/no-useless-computed-key + 'no-useless-computed-key': 'error', + + // disallow unnecessary constructor + // https://eslint.org/docs/rules/no-useless-constructor + 'no-useless-constructor': 'error', + + // disallow renaming import, export, and destructured assignments to the same name + // https://eslint.org/docs/rules/no-useless-rename + 'no-useless-rename': ['error', { + ignoreDestructuring: false, + ignoreImport: false, + ignoreExport: false, + }], + + // require let or const instead of var + 'no-var': 'error', + + // require method and property shorthand syntax for object literals + // https://eslint.org/docs/rules/object-shorthand + 'object-shorthand': ['error', 'always', { + ignoreConstructors: false, + avoidQuotes: true, + }], + + // suggest using arrow functions as callbacks + 'prefer-arrow-callback': ['error', { + allowNamedFunctions: false, + allowUnboundThis: true, + }], + + // suggest using of const declaration for variables that are never modified after declared + 'prefer-const': ['error', { + destructuring: 'any', + ignoreReadBeforeAssign: true, + }], + + // Prefer destructuring from arrays and objects + // https://eslint.org/docs/rules/prefer-destructuring + 'prefer-destructuring': ['error', { + VariableDeclarator: { + array: false, + object: true, + }, + AssignmentExpression: { + array: true, + object: false, + }, + }, { + enforceForRenamedProperties: false, + }], + + // disallow parseInt() in favor of binary, octal, and hexadecimal literals + // https://eslint.org/docs/rules/prefer-numeric-literals + 'prefer-numeric-literals': 'error', + + // suggest using Reflect methods where applicable + // https://eslint.org/docs/rules/prefer-reflect + 'prefer-reflect': 'off', + + // use rest parameters instead of arguments + // https://eslint.org/docs/rules/prefer-rest-params + 'prefer-rest-params': 'error', + + // suggest using the spread syntax instead of .apply() + // https://eslint.org/docs/rules/prefer-spread + 'prefer-spread': 'error', + + // suggest using template literals instead of string concatenation + // https://eslint.org/docs/rules/prefer-template + 'prefer-template': 'error', + + // disallow generator functions that do not have yield + // https://eslint.org/docs/rules/require-yield + 'require-yield': 'error', + + // enforce spacing between object rest-spread + // https://eslint.org/docs/rules/rest-spread-spacing + 'rest-spread-spacing': ['error', 'never'], + + // import sorting + // https://eslint.org/docs/rules/sort-imports + 'sort-imports': ['off', { + ignoreCase: false, + ignoreDeclarationSort: false, + ignoreMemberSort: false, + memberSyntaxSortOrder: ['none', 'all', 'multiple', 'single'], + }], + + // require a Symbol description + // https://eslint.org/docs/rules/symbol-description + 'symbol-description': 'error', + + // enforce usage of spacing in template strings + // https://eslint.org/docs/rules/template-curly-spacing + 'template-curly-spacing': 'error', + + // enforce spacing around the * in yield* expressions + // https://eslint.org/docs/rules/yield-star-spacing + 'yield-star-spacing': ['error', 'after'] + } +}; diff --git a/packages/eslint-config-airbnb-base/rules/imports.js b/packages/eslint-config-airbnb-base/rules/imports.js new file mode 100644 index 0000000000..d36e4908fa --- /dev/null +++ b/packages/eslint-config-airbnb-base/rules/imports.js @@ -0,0 +1,283 @@ +module.exports = { + env: { + es6: true + }, + parserOptions: { + ecmaVersion: 6, + sourceType: 'module' + }, + plugins: [ + 'import' + ], + + settings: { + 'import/resolver': { + node: { + extensions: ['.mjs', '.js', '.json'] + } + }, + 'import/extensions': [ + '.js', + '.mjs', + '.jsx', + ], + 'import/core-modules': [ + ], + 'import/ignore': [ + 'node_modules', + '\\.(coffee|scss|css|less|hbs|svg|json)$', + ], + }, + + rules: { + // Static analysis: + + // ensure imports point to files/modules that can be resolved + // https://github.com/import-js/eslint-plugin-import/blob/master/docs/rules/no-unresolved.md + 'import/no-unresolved': ['error', { commonjs: true, caseSensitive: true }], + + // ensure named imports coupled with named exports + // https://github.com/import-js/eslint-plugin-import/blob/master/docs/rules/named.md#when-not-to-use-it + 'import/named': 'error', + + // ensure default import coupled with default export + // https://github.com/import-js/eslint-plugin-import/blob/master/docs/rules/default.md#when-not-to-use-it + 'import/default': 'off', + + // https://github.com/import-js/eslint-plugin-import/blob/master/docs/rules/namespace.md + 'import/namespace': 'off', + + // Helpful warnings: + + // disallow invalid exports, e.g. multiple defaults + // https://github.com/import-js/eslint-plugin-import/blob/master/docs/rules/export.md + 'import/export': 'error', + + // do not allow a default import name to match a named export + // https://github.com/import-js/eslint-plugin-import/blob/master/docs/rules/no-named-as-default.md + 'import/no-named-as-default': 'error', + + // warn on accessing default export property names that are also named exports + // https://github.com/import-js/eslint-plugin-import/blob/master/docs/rules/no-named-as-default-member.md + 'import/no-named-as-default-member': 'error', + + // disallow use of jsdoc-marked-deprecated imports + // https://github.com/import-js/eslint-plugin-import/blob/master/docs/rules/no-deprecated.md + 'import/no-deprecated': 'off', + + // Forbid the use of extraneous packages + // https://github.com/import-js/eslint-plugin-import/blob/master/docs/rules/no-extraneous-dependencies.md + // paths are treated both as absolute paths, and relative to process.cwd() + 'import/no-extraneous-dependencies': ['error', { + devDependencies: [ + 'test/**', // tape, common npm pattern + 'tests/**', // also common npm pattern + 'spec/**', // mocha, rspec-like pattern + '**/__tests__/**', // jest pattern + '**/__mocks__/**', // jest pattern + 'test.{js,jsx}', // repos with a single test file + 'test-*.{js,jsx}', // repos with multiple top-level test files + '**/*{.,_}{test,spec}.{js,jsx}', // tests where the extension or filename suffix denotes that it is a test + '**/jest.config.js', // jest config + '**/jest.setup.js', // jest setup + '**/vue.config.js', // vue-cli config + '**/webpack.config.js', // webpack config + '**/webpack.config.*.js', // webpack config + '**/rollup.config.js', // rollup config + '**/rollup.config.*.js', // rollup config + '**/gulpfile.js', // gulp config + '**/gulpfile.*.js', // gulp config + '**/Gruntfile{,.js}', // grunt config + '**/protractor.conf.js', // protractor config + '**/protractor.conf.*.js', // protractor config + '**/karma.conf.js', // karma config + '**/.eslintrc.js' // eslint config + ], + optionalDependencies: false, + }], + + // Forbid mutable exports + // https://github.com/import-js/eslint-plugin-import/blob/master/docs/rules/no-mutable-exports.md + 'import/no-mutable-exports': 'error', + + // Module systems: + + // disallow require() + // https://github.com/import-js/eslint-plugin-import/blob/master/docs/rules/no-commonjs.md + 'import/no-commonjs': 'off', + + // disallow AMD require/define + // https://github.com/import-js/eslint-plugin-import/blob/master/docs/rules/no-amd.md + 'import/no-amd': 'error', + + // No Node.js builtin modules + // https://github.com/import-js/eslint-plugin-import/blob/master/docs/rules/no-nodejs-modules.md + // TODO: enable? + 'import/no-nodejs-modules': 'off', + + // Style guide: + + // disallow non-import statements appearing before import statements + // https://github.com/import-js/eslint-plugin-import/blob/master/docs/rules/first.md + 'import/first': 'error', + + // disallow non-import statements appearing before import statements + // https://github.com/import-js/eslint-plugin-import/blob/master/docs/rules/imports-first.md + // deprecated: use `import/first` + 'import/imports-first': 'off', + + // disallow duplicate imports + // https://github.com/import-js/eslint-plugin-import/blob/master/docs/rules/no-duplicates.md + 'import/no-duplicates': 'error', + + // disallow namespace imports + // TODO: enable? + // https://github.com/import-js/eslint-plugin-import/blob/master/docs/rules/no-namespace.md + 'import/no-namespace': 'off', + + // Ensure consistent use of file extension within the import path + // https://github.com/import-js/eslint-plugin-import/blob/master/docs/rules/extensions.md + 'import/extensions': ['error', 'ignorePackages', { + js: 'never', + mjs: 'never', + jsx: 'never', + }], + + // ensure absolute imports are above relative imports and that unassigned imports are ignored + // https://github.com/import-js/eslint-plugin-import/blob/master/docs/rules/order.md + // TODO: enforce a stricter convention in module import order? + 'import/order': ['error', { groups: [['builtin', 'external', 'internal']] }], + + // Require a newline after the last import/require in a group + // https://github.com/import-js/eslint-plugin-import/blob/master/docs/rules/newline-after-import.md + 'import/newline-after-import': 'error', + + // Require modules with a single export to use a default export + // https://github.com/import-js/eslint-plugin-import/blob/master/docs/rules/prefer-default-export.md + 'import/prefer-default-export': 'error', + + // Restrict which files can be imported in a given folder + // https://github.com/import-js/eslint-plugin-import/blob/master/docs/rules/no-restricted-paths.md + 'import/no-restricted-paths': 'off', + + // Forbid modules to have too many dependencies + // https://github.com/import-js/eslint-plugin-import/blob/master/docs/rules/max-dependencies.md + 'import/max-dependencies': ['off', { max: 10 }], + + // Forbid import of modules using absolute paths + // https://github.com/import-js/eslint-plugin-import/blob/master/docs/rules/no-absolute-path.md + 'import/no-absolute-path': 'error', + + // Forbid require() calls with expressions + // https://github.com/import-js/eslint-plugin-import/blob/master/docs/rules/no-dynamic-require.md + 'import/no-dynamic-require': 'error', + + // prevent importing the submodules of other modules + // https://github.com/import-js/eslint-plugin-import/blob/master/docs/rules/no-internal-modules.md + 'import/no-internal-modules': ['off', { + allow: [], + }], + + // Warn if a module could be mistakenly parsed as a script by a consumer + // leveraging Unambiguous JavaScript Grammar + // https://github.com/import-js/eslint-plugin-import/blob/master/docs/rules/unambiguous.md + // this should not be enabled until this proposal has at least been *presented* to TC39. + // At the moment, it's not a thing. + 'import/unambiguous': 'off', + + // Forbid Webpack loader syntax in imports + // https://github.com/import-js/eslint-plugin-import/blob/master/docs/rules/no-webpack-loader-syntax.md + 'import/no-webpack-loader-syntax': 'error', + + // Prevent unassigned imports + // https://github.com/import-js/eslint-plugin-import/blob/master/docs/rules/no-unassigned-import.md + // importing for side effects is perfectly acceptable, if you need side effects. + 'import/no-unassigned-import': 'off', + + // Prevent importing the default as if it were named + // https://github.com/import-js/eslint-plugin-import/blob/master/docs/rules/no-named-default.md + 'import/no-named-default': 'error', + + // Reports if a module's default export is unnamed + // https://github.com/import-js/eslint-plugin-import/blob/d9b712ac7fd1fddc391f7b234827925c160d956f/docs/rules/no-anonymous-default-export.md + 'import/no-anonymous-default-export': ['off', { + allowArray: false, + allowArrowFunction: false, + allowAnonymousClass: false, + allowAnonymousFunction: false, + allowLiteral: false, + allowObject: false, + }], + + // This rule enforces that all exports are declared at the bottom of the file. + // https://github.com/import-js/eslint-plugin-import/blob/98acd6afd04dcb6920b81330114e146dc8532ea4/docs/rules/exports-last.md + // TODO: enable? + 'import/exports-last': 'off', + + // Reports when named exports are not grouped together in a single export declaration + // or when multiple assignments to CommonJS module.exports or exports object are present + // in a single file. + // https://github.com/import-js/eslint-plugin-import/blob/44a038c06487964394b1e15b64f3bd34e5d40cde/docs/rules/group-exports.md + 'import/group-exports': 'off', + + // forbid default exports. this is a terrible rule, do not use it. + // https://github.com/import-js/eslint-plugin-import/blob/44a038c06487964394b1e15b64f3bd34e5d40cde/docs/rules/no-default-export.md + 'import/no-default-export': 'off', + + // Prohibit named exports. this is a terrible rule, do not use it. + // https://github.com/import-js/eslint-plugin-import/blob/1ec80fa35fa1819e2d35a70e68fb6a149fb57c5e/docs/rules/no-named-export.md + 'import/no-named-export': 'off', + + // Forbid a module from importing itself + // https://github.com/import-js/eslint-plugin-import/blob/44a038c06487964394b1e15b64f3bd34e5d40cde/docs/rules/no-self-import.md + 'import/no-self-import': 'error', + + // Forbid cyclical dependencies between modules + // https://github.com/import-js/eslint-plugin-import/blob/d81f48a2506182738409805f5272eff4d77c9348/docs/rules/no-cycle.md + 'import/no-cycle': ['error', { maxDepth: '∞' }], + + // Ensures that there are no useless path segments + // https://github.com/import-js/eslint-plugin-import/blob/ebafcbf59ec9f653b2ac2a0156ca3bcba0a7cf57/docs/rules/no-useless-path-segments.md + 'import/no-useless-path-segments': ['error', { commonjs: true }], + + // dynamic imports require a leading comment with a webpackChunkName + // https://github.com/import-js/eslint-plugin-import/blob/ebafcbf59ec9f653b2ac2a0156ca3bcba0a7cf57/docs/rules/dynamic-import-chunkname.md + 'import/dynamic-import-chunkname': ['off', { + importFunctions: [], + webpackChunknameFormat: '[0-9a-zA-Z-_/.]+', + }], + + // Use this rule to prevent imports to folders in relative parent paths. + // https://github.com/import-js/eslint-plugin-import/blob/c34f14f67f077acd5a61b3da9c0b0de298d20059/docs/rules/no-relative-parent-imports.md + 'import/no-relative-parent-imports': 'off', + + // Reports modules without any exports, or with unused exports + // https://github.com/import-js/eslint-plugin-import/blob/f63dd261809de6883b13b6b5b960e6d7f42a7813/docs/rules/no-unused-modules.md + // TODO: enable once it supports CJS + 'import/no-unused-modules': ['off', { + ignoreExports: [], + missingExports: true, + unusedExports: true, + }], + + // Reports the use of import declarations with CommonJS exports in any module except for the main module. + // https://github.com/import-js/eslint-plugin-import/blob/1012eb951767279ce3b540a4ec4f29236104bb5b/docs/rules/no-import-module-exports.md + 'import/no-import-module-exports': ['error', { + exceptions: [], + }], + + // Use this rule to prevent importing packages through relative paths. + // https://github.com/import-js/eslint-plugin-import/blob/1012eb951767279ce3b540a4ec4f29236104bb5b/docs/rules/no-relative-packages.md + 'import/no-relative-packages': 'error', + + // enforce a consistent style for type specifiers (inline or top-level) + // https://github.com/import-js/eslint-plugin-import/blob/d5fc8b670dc8e6903dbb7b0894452f60c03089f5/docs/rules/consistent-type-specifier-style.md + // TODO, semver-major: enable (just in case) + 'import/consistent-type-specifier-style': ['off', 'prefer-inline'], + + // Reports the use of empty named import blocks. + // https://github.com/import-js/eslint-plugin-import/blob/d5fc8b670dc8e6903dbb7b0894452f60c03089f5/docs/rules/no-empty-named-blocks.md + // TODO, semver-minor: enable + 'import/no-empty-named-blocks': 'off', + }, +}; diff --git a/packages/eslint-config-airbnb-base/rules/node.js b/packages/eslint-config-airbnb-base/rules/node.js new file mode 100644 index 0000000000..b178d7f909 --- /dev/null +++ b/packages/eslint-config-airbnb-base/rules/node.js @@ -0,0 +1,43 @@ +module.exports = { + env: { + node: true + }, + + rules: { + // enforce return after a callback + 'callback-return': 'off', + + // require all requires be top-level + // https://eslint.org/docs/rules/global-require + 'global-require': 'error', + + // enforces error handling in callbacks (node environment) + 'handle-callback-err': 'off', + + // disallow use of the Buffer() constructor + // https://eslint.org/docs/rules/no-buffer-constructor + 'no-buffer-constructor': 'error', + + // disallow mixing regular variable and require declarations + 'no-mixed-requires': ['off', false], + + // disallow use of new operator with the require function + 'no-new-require': 'error', + + // disallow string concatenation with __dirname and __filename + // https://eslint.org/docs/rules/no-path-concat + 'no-path-concat': 'error', + + // disallow use of process.env + 'no-process-env': 'off', + + // disallow process.exit() + 'no-process-exit': 'off', + + // restrict usage of specified node modules + 'no-restricted-modules': 'off', + + // disallow use of synchronous methods (off by default) + 'no-sync': 'off', + } +}; diff --git a/packages/eslint-config-airbnb-base/rules/strict.js b/packages/eslint-config-airbnb-base/rules/strict.js new file mode 100644 index 0000000000..67cfd5e8a3 --- /dev/null +++ b/packages/eslint-config-airbnb-base/rules/strict.js @@ -0,0 +1,6 @@ +module.exports = { + rules: { + // babel inserts `'use strict';` for us + strict: ['error', 'never'] + } +}; diff --git a/packages/eslint-config-airbnb-base/rules/style.js b/packages/eslint-config-airbnb-base/rules/style.js new file mode 100644 index 0000000000..2e7f6fed44 --- /dev/null +++ b/packages/eslint-config-airbnb-base/rules/style.js @@ -0,0 +1,534 @@ +module.exports = { + rules: { + // enforce line breaks after opening and before closing array brackets + // https://eslint.org/docs/rules/array-bracket-newline + // TODO: enable? semver-major + 'array-bracket-newline': ['off', 'consistent'], // object option alternative: { multiline: true, minItems: 3 } + + // enforce line breaks between array elements + // https://eslint.org/docs/rules/array-element-newline + // TODO: enable? semver-major + 'array-element-newline': ['off', { multiline: true, minItems: 3 }], + + // enforce spacing inside array brackets + 'array-bracket-spacing': ['error', 'never'], + + // enforce spacing inside single-line blocks + // https://eslint.org/docs/rules/block-spacing + 'block-spacing': ['error', 'always'], + + // enforce one true brace style + 'brace-style': ['error', '1tbs', { allowSingleLine: true }], + + // require camel case names + camelcase: ['error', { properties: 'never', ignoreDestructuring: false }], + + // enforce or disallow capitalization of the first letter of a comment + // https://eslint.org/docs/rules/capitalized-comments + 'capitalized-comments': ['off', 'never', { + line: { + ignorePattern: '.*', + ignoreInlineComments: true, + ignoreConsecutiveComments: true, + }, + block: { + ignorePattern: '.*', + ignoreInlineComments: true, + ignoreConsecutiveComments: true, + }, + }], + + // require trailing commas in multiline object literals + 'comma-dangle': ['error', { + arrays: 'always-multiline', + objects: 'always-multiline', + imports: 'always-multiline', + exports: 'always-multiline', + functions: 'always-multiline', + }], + + // enforce spacing before and after comma + 'comma-spacing': ['error', { before: false, after: true }], + + // enforce one true comma style + 'comma-style': ['error', 'last', { + exceptions: { + ArrayExpression: false, + ArrayPattern: false, + ArrowFunctionExpression: false, + CallExpression: false, + FunctionDeclaration: false, + FunctionExpression: false, + ImportDeclaration: false, + ObjectExpression: false, + ObjectPattern: false, + VariableDeclaration: false, + NewExpression: false, + } + }], + + // disallow padding inside computed properties + 'computed-property-spacing': ['error', 'never'], + + // enforces consistent naming when capturing the current execution context + 'consistent-this': 'off', + + // enforce newline at the end of file, with no multiple empty lines + 'eol-last': ['error', 'always'], + + // https://eslint.org/docs/rules/function-call-argument-newline + 'function-call-argument-newline': ['error', 'consistent'], + + // enforce spacing between functions and their invocations + // https://eslint.org/docs/rules/func-call-spacing + 'func-call-spacing': ['error', 'never'], + + // requires function names to match the name of the variable or property to which they are + // assigned + // https://eslint.org/docs/rules/func-name-matching + 'func-name-matching': ['off', 'always', { + includeCommonJSModuleExports: false, + considerPropertyDescriptor: true, + }], + + // require function expressions to have a name + // https://eslint.org/docs/rules/func-names + 'func-names': 'warn', + + // enforces use of function declarations or expressions + // https://eslint.org/docs/rules/func-style + // TODO: enable + 'func-style': ['off', 'expression'], + + // require line breaks inside function parentheses if there are line breaks between parameters + // https://eslint.org/docs/rules/function-paren-newline + 'function-paren-newline': ['error', 'multiline-arguments'], + + // disallow specified identifiers + // https://eslint.org/docs/rules/id-denylist + 'id-denylist': 'off', + + // this option enforces minimum and maximum identifier lengths + // (variable names, property names etc.) + 'id-length': 'off', + + // require identifiers to match the provided regular expression + 'id-match': 'off', + + // Enforce the location of arrow function bodies with implicit returns + // https://eslint.org/docs/rules/implicit-arrow-linebreak + 'implicit-arrow-linebreak': ['error', 'beside'], + + // this option sets a specific tab width for your code + // https://eslint.org/docs/rules/indent + indent: ['error', 2, { + SwitchCase: 1, + VariableDeclarator: 1, + outerIIFEBody: 1, + // MemberExpression: null, + FunctionDeclaration: { + parameters: 1, + body: 1 + }, + FunctionExpression: { + parameters: 1, + body: 1 + }, + CallExpression: { + arguments: 1 + }, + ArrayExpression: 1, + ObjectExpression: 1, + ImportDeclaration: 1, + flatTernaryExpressions: false, + // list derived from https://github.com/benjamn/ast-types/blob/HEAD/def/jsx.js + ignoredNodes: ['JSXElement', 'JSXElement > *', 'JSXAttribute', 'JSXIdentifier', 'JSXNamespacedName', 'JSXMemberExpression', 'JSXSpreadAttribute', 'JSXExpressionContainer', 'JSXOpeningElement', 'JSXClosingElement', 'JSXFragment', 'JSXOpeningFragment', 'JSXClosingFragment', 'JSXText', 'JSXEmptyExpression', 'JSXSpreadChild'], + ignoreComments: false + }], + + // specify whether double or single quotes should be used in JSX attributes + // https://eslint.org/docs/rules/jsx-quotes + 'jsx-quotes': ['off', 'prefer-double'], + + // enforces spacing between keys and values in object literal properties + 'key-spacing': ['error', { beforeColon: false, afterColon: true }], + + // require a space before & after certain keywords + 'keyword-spacing': ['error', { + before: true, + after: true, + overrides: { + return: { after: true }, + throw: { after: true }, + case: { after: true } + } + }], + + // enforce position of line comments + // https://eslint.org/docs/rules/line-comment-position + // TODO: enable? + 'line-comment-position': ['off', { + position: 'above', + ignorePattern: '', + applyDefaultPatterns: true, + }], + + // disallow mixed 'LF' and 'CRLF' as linebreaks + // https://eslint.org/docs/rules/linebreak-style + 'linebreak-style': ['error', 'unix'], + + // require or disallow an empty line between class members + // https://eslint.org/docs/rules/lines-between-class-members + 'lines-between-class-members': ['error', 'always', { exceptAfterSingleLine: false }], + + // enforces empty lines around comments + 'lines-around-comment': 'off', + + // require or disallow newlines around directives + // https://eslint.org/docs/rules/lines-around-directive + 'lines-around-directive': ['error', { + before: 'always', + after: 'always', + }], + + // Require or disallow logical assignment logical operator shorthand + // https://eslint.org/docs/latest/rules/logical-assignment-operators + // TODO, semver-major: enable + 'logical-assignment-operators': ['off', 'always', { + enforceForIfStatements: true, + }], + + // specify the maximum depth that blocks can be nested + 'max-depth': ['off', 4], + + // specify the maximum length of a line in your program + // https://eslint.org/docs/rules/max-len + 'max-len': ['error', 100, 2, { + ignoreUrls: true, + ignoreComments: false, + ignoreRegExpLiterals: true, + ignoreStrings: true, + ignoreTemplateLiterals: true, + }], + + // specify the max number of lines in a file + // https://eslint.org/docs/rules/max-lines + 'max-lines': ['off', { + max: 300, + skipBlankLines: true, + skipComments: true + }], + + // enforce a maximum function length + // https://eslint.org/docs/rules/max-lines-per-function + 'max-lines-per-function': ['off', { + max: 50, + skipBlankLines: true, + skipComments: true, + IIFEs: true, + }], + + // specify the maximum depth callbacks can be nested + 'max-nested-callbacks': 'off', + + // limits the number of parameters that can be used in the function declaration. + 'max-params': ['off', 3], + + // specify the maximum number of statement allowed in a function + 'max-statements': ['off', 10], + + // restrict the number of statements per line + // https://eslint.org/docs/rules/max-statements-per-line + 'max-statements-per-line': ['off', { max: 1 }], + + // enforce a particular style for multiline comments + // https://eslint.org/docs/rules/multiline-comment-style + 'multiline-comment-style': ['off', 'starred-block'], + + // require multiline ternary + // https://eslint.org/docs/rules/multiline-ternary + // TODO: enable? + 'multiline-ternary': ['off', 'never'], + + // require a capital letter for constructors + 'new-cap': ['error', { + newIsCap: true, + newIsCapExceptions: [], + capIsNew: false, + capIsNewExceptions: ['Immutable.Map', 'Immutable.Set', 'Immutable.List'], + }], + + // disallow the omission of parentheses when invoking a constructor with no arguments + // https://eslint.org/docs/rules/new-parens + 'new-parens': 'error', + + // allow/disallow an empty newline after var statement + 'newline-after-var': 'off', + + // https://eslint.org/docs/rules/newline-before-return + 'newline-before-return': 'off', + + // enforces new line after each method call in the chain to make it + // more readable and easy to maintain + // https://eslint.org/docs/rules/newline-per-chained-call + 'newline-per-chained-call': ['error', { ignoreChainWithDepth: 4 }], + + // disallow use of the Array constructor + 'no-array-constructor': 'error', + + // disallow use of bitwise operators + // https://eslint.org/docs/rules/no-bitwise + 'no-bitwise': 'error', + + // disallow use of the continue statement + // https://eslint.org/docs/rules/no-continue + 'no-continue': 'error', + + // disallow comments inline after code + 'no-inline-comments': 'off', + + // disallow if as the only statement in an else block + // https://eslint.org/docs/rules/no-lonely-if + 'no-lonely-if': 'error', + + // disallow un-paren'd mixes of different operators + // https://eslint.org/docs/rules/no-mixed-operators + 'no-mixed-operators': ['error', { + // the list of arithmetic groups disallows mixing `%` and `**` + // with other arithmetic operators. + groups: [ + ['%', '**'], + ['%', '+'], + ['%', '-'], + ['%', '*'], + ['%', '/'], + ['/', '*'], + ['&', '|', '<<', '>>', '>>>'], + ['==', '!=', '===', '!=='], + ['&&', '||'], + ], + allowSamePrecedence: false + }], + + // disallow mixed spaces and tabs for indentation + 'no-mixed-spaces-and-tabs': 'error', + + // disallow use of chained assignment expressions + // https://eslint.org/docs/rules/no-multi-assign + 'no-multi-assign': ['error'], + + // disallow multiple empty lines, only one newline at the end, and no new lines at the beginning + // https://eslint.org/docs/rules/no-multiple-empty-lines + 'no-multiple-empty-lines': ['error', { max: 1, maxBOF: 0, maxEOF: 0 }], + + // disallow negated conditions + // https://eslint.org/docs/rules/no-negated-condition + 'no-negated-condition': 'off', + + // disallow nested ternary expressions + 'no-nested-ternary': 'error', + + // disallow use of the Object constructor + 'no-new-object': 'error', + + // disallow use of unary operators, ++ and -- + // https://eslint.org/docs/rules/no-plusplus + 'no-plusplus': 'error', + + // disallow certain syntax forms + // https://eslint.org/docs/rules/no-restricted-syntax + 'no-restricted-syntax': [ + 'error', + { + selector: 'ForInStatement', + message: 'for..in loops iterate over the entire prototype chain, which is virtually never what you want. Use Object.{keys,values,entries}, and iterate over the resulting array.', + }, + { + selector: 'ForOfStatement', + message: 'iterators/generators require regenerator-runtime, which is too heavyweight for this guide to allow them. Separately, loops should be avoided in favor of array iterations.', + }, + { + selector: 'LabeledStatement', + message: 'Labels are a form of GOTO; using them makes code confusing and hard to maintain and understand.', + }, + { + selector: 'WithStatement', + message: '`with` is disallowed in strict mode because it makes code impossible to predict and optimize.', + }, + ], + + // disallow space between function identifier and application + // deprecated in favor of func-call-spacing + 'no-spaced-func': 'off', + + // disallow tab characters entirely + 'no-tabs': 'error', + + // disallow the use of ternary operators + 'no-ternary': 'off', + + // disallow trailing whitespace at the end of lines + 'no-trailing-spaces': ['error', { + skipBlankLines: false, + ignoreComments: false, + }], + + // disallow dangling underscores in identifiers + // https://eslint.org/docs/rules/no-underscore-dangle + 'no-underscore-dangle': ['error', { + allow: [], + allowAfterThis: false, + allowAfterSuper: false, + enforceInMethodNames: true, + }], + + // disallow the use of Boolean literals in conditional expressions + // also, prefer `a || b` over `a ? a : b` + // https://eslint.org/docs/rules/no-unneeded-ternary + 'no-unneeded-ternary': ['error', { defaultAssignment: false }], + + // disallow whitespace before properties + // https://eslint.org/docs/rules/no-whitespace-before-property + 'no-whitespace-before-property': 'error', + + // enforce the location of single-line statements + // https://eslint.org/docs/rules/nonblock-statement-body-position + 'nonblock-statement-body-position': ['error', 'beside', { overrides: {} }], + + // require padding inside curly braces + 'object-curly-spacing': ['error', 'always'], + + // enforce line breaks between braces + // https://eslint.org/docs/rules/object-curly-newline + 'object-curly-newline': ['error', { + ObjectExpression: { minProperties: 4, multiline: true, consistent: true }, + ObjectPattern: { minProperties: 4, multiline: true, consistent: true }, + ImportDeclaration: { minProperties: 4, multiline: true, consistent: true }, + ExportDeclaration: { minProperties: 4, multiline: true, consistent: true }, + }], + + // enforce "same line" or "multiple line" on object properties. + // https://eslint.org/docs/rules/object-property-newline + 'object-property-newline': ['error', { + allowAllPropertiesOnSameLine: true, + }], + + // allow just one var statement per function + 'one-var': ['error', 'never'], + + // require a newline around variable declaration + // https://eslint.org/docs/rules/one-var-declaration-per-line + 'one-var-declaration-per-line': ['error', 'always'], + + // require assignment operator shorthand where possible or prohibit it entirely + // https://eslint.org/docs/rules/operator-assignment + 'operator-assignment': ['error', 'always'], + + // Requires operator at the beginning of the line in multiline statements + // https://eslint.org/docs/rules/operator-linebreak + 'operator-linebreak': ['error', 'before', { overrides: { '=': 'none' } }], + + // disallow padding within blocks + 'padded-blocks': ['error', { + blocks: 'never', + classes: 'never', + switches: 'never', + }, { + allowSingleLineBlocks: true, + }], + + // Require or disallow padding lines between statements + // https://eslint.org/docs/rules/padding-line-between-statements + 'padding-line-between-statements': 'off', + + // Disallow the use of Math.pow in favor of the ** operator + // https://eslint.org/docs/rules/prefer-exponentiation-operator + 'prefer-exponentiation-operator': 'error', + + // Prefer use of an object spread over Object.assign + // https://eslint.org/docs/rules/prefer-object-spread + 'prefer-object-spread': 'error', + + // require quotes around object literal property names + // https://eslint.org/docs/rules/quote-props.html + 'quote-props': ['error', 'as-needed', { keywords: false, unnecessary: true, numbers: false }], + + // specify whether double or single quotes should be used + quotes: ['error', 'single', { avoidEscape: true }], + + // do not require jsdoc + // https://eslint.org/docs/rules/require-jsdoc + 'require-jsdoc': 'off', + + // require or disallow use of semicolons instead of ASI + semi: ['error', 'always'], + + // enforce spacing before and after semicolons + 'semi-spacing': ['error', { before: false, after: true }], + + // Enforce location of semicolons + // https://eslint.org/docs/rules/semi-style + 'semi-style': ['error', 'last'], + + // requires object keys to be sorted + 'sort-keys': ['off', 'asc', { caseSensitive: false, natural: true }], + + // sort variables within the same declaration block + 'sort-vars': 'off', + + // require or disallow space before blocks + 'space-before-blocks': 'error', + + // require or disallow space before function opening parenthesis + // https://eslint.org/docs/rules/space-before-function-paren + 'space-before-function-paren': ['error', { + anonymous: 'always', + named: 'never', + asyncArrow: 'always' + }], + + // require or disallow spaces inside parentheses + 'space-in-parens': ['error', 'never'], + + // require spaces around operators + 'space-infix-ops': 'error', + + // Require or disallow spaces before/after unary operators + // https://eslint.org/docs/rules/space-unary-ops + 'space-unary-ops': ['error', { + words: true, + nonwords: false, + overrides: { + }, + }], + + // require or disallow a space immediately following the // or /* in a comment + // https://eslint.org/docs/rules/spaced-comment + 'spaced-comment': ['error', 'always', { + line: { + exceptions: ['-', '+'], + markers: ['=', '!', '/'], // space here to support sprockets directives, slash for TS /// comments + }, + block: { + exceptions: ['-', '+'], + markers: ['=', '!', ':', '::'], // space here to support sprockets directives and flow comment types + balanced: true, + } + }], + + // Enforce spacing around colons of switch statements + // https://eslint.org/docs/rules/switch-colon-spacing + 'switch-colon-spacing': ['error', { after: true, before: false }], + + // Require or disallow spacing between template tags and their literals + // https://eslint.org/docs/rules/template-tag-spacing + 'template-tag-spacing': ['error', 'never'], + + // require or disallow the Unicode Byte Order Mark + // https://eslint.org/docs/rules/unicode-bom + 'unicode-bom': ['error', 'never'], + + // require regex literals to be wrapped in parentheses + 'wrap-regex': 'off' + } +}; diff --git a/packages/eslint-config-airbnb-base/rules/variables.js b/packages/eslint-config-airbnb-base/rules/variables.js new file mode 100644 index 0000000000..7d61989e6a --- /dev/null +++ b/packages/eslint-config-airbnb-base/rules/variables.js @@ -0,0 +1,59 @@ +const confusingBrowserGlobals = require('confusing-browser-globals'); + +module.exports = { + rules: { + // enforce or disallow variable initializations at definition + 'init-declarations': 'off', + + // disallow the catch clause parameter name being the same as a variable in the outer scope + 'no-catch-shadow': 'off', + + // disallow deletion of variables + 'no-delete-var': 'error', + + // disallow labels that share a name with a variable + // https://eslint.org/docs/rules/no-label-var + 'no-label-var': 'error', + + // disallow specific globals + 'no-restricted-globals': [ + 'error', + { + name: 'isFinite', + message: + 'Use Number.isFinite instead https://github.com/airbnb/javascript#standard-library--isfinite', + }, + { + name: 'isNaN', + message: + 'Use Number.isNaN instead https://github.com/airbnb/javascript#standard-library--isnan', + }, + ].concat(confusingBrowserGlobals.map((g) => ({ + name: g, + message: `Use window.${g} instead. https://github.com/facebook/create-react-app/blob/HEAD/packages/confusing-browser-globals/README.md`, + }))), + + // disallow declaration of variables already declared in the outer scope + 'no-shadow': 'error', + + // disallow shadowing of names such as arguments + 'no-shadow-restricted-names': 'error', + + // disallow use of undeclared variables unless mentioned in a /*global */ block + 'no-undef': 'error', + + // disallow use of undefined when initializing variables + 'no-undef-init': 'error', + + // disallow use of undefined variable + // https://eslint.org/docs/rules/no-undefined + // TODO: enable? + 'no-undefined': 'off', + + // disallow declaration of variables that are not used in the code + 'no-unused-vars': ['error', { vars: 'all', args: 'after-used', ignoreRestSiblings: true }], + + // disallow use of variables before they are defined + 'no-use-before-define': ['error', { functions: true, classes: true, variables: true }], + } +}; diff --git a/packages/eslint-config-airbnb-base/test/.eslintrc b/packages/eslint-config-airbnb-base/test/.eslintrc new file mode 100644 index 0000000000..5808be6186 --- /dev/null +++ b/packages/eslint-config-airbnb-base/test/.eslintrc @@ -0,0 +1,8 @@ +{ + "rules": { + // disabled because I find it tedious to write tests while following this rule + "no-shadow": 0, + // tests uses `t` for tape + "id-length": [2, {"min": 2, "properties": "never", "exceptions": ["t"]}], + } +} diff --git a/packages/eslint-config-airbnb-base/test/requires.js b/packages/eslint-config-airbnb-base/test/requires.js new file mode 100644 index 0000000000..8176480fe1 --- /dev/null +++ b/packages/eslint-config-airbnb-base/test/requires.js @@ -0,0 +1,13 @@ +/* eslint strict: 0, global-require: 0 */ + +'use strict'; + +const test = require('tape'); + +test('all entry points parse', (t) => { + t.doesNotThrow(() => require('..'), 'index does not throw'); + t.doesNotThrow(() => require('../legacy'), 'legacy does not throw'); + t.doesNotThrow(() => require('../whitespace'), 'whitespace does not throw'); + + t.end(); +}); diff --git a/packages/eslint-config-airbnb-base/test/test-base.js b/packages/eslint-config-airbnb-base/test/test-base.js new file mode 100644 index 0000000000..4380bf5567 --- /dev/null +++ b/packages/eslint-config-airbnb-base/test/test-base.js @@ -0,0 +1,33 @@ +import fs from 'fs'; +import path from 'path'; +import test from 'tape'; + +import index from '..'; + +const files = { ...{ index } }; // object spread is to test parsing + +const rulesDir = path.join(__dirname, '../rules'); +fs.readdirSync(rulesDir).forEach((name) => { + // eslint-disable-next-line import/no-dynamic-require + files[name] = require(path.join(rulesDir, name)); // eslint-disable-line global-require +}); + +Object.keys(files).forEach(( + name, // trailing function comma is to test parsing +) => { + const config = files[name]; + + test(`${name}: does not reference react`, (t) => { + t.plan(2); + + // scan plugins for react and fail if it is found + const hasReactPlugin = Object.prototype.hasOwnProperty.call(config, 'plugins') + && config.plugins.indexOf('react') !== -1; + t.notOk(hasReactPlugin, 'there is no react plugin'); + + // scan rules for react/ and fail if any exist + const reactRuleIds = Object.keys(config.rules) + .filter((ruleId) => ruleId.indexOf('react/') === 0); + t.deepEquals(reactRuleIds, [], 'there are no react/ rules'); + }); +}); diff --git a/packages/eslint-config-airbnb-base/whitespace-async.js b/packages/eslint-config-airbnb-base/whitespace-async.js new file mode 100755 index 0000000000..06f4f89075 --- /dev/null +++ b/packages/eslint-config-airbnb-base/whitespace-async.js @@ -0,0 +1,49 @@ +#!/usr/bin/env node + +const { isArray } = Array; +const { entries } = Object; +const { ESLint } = require('eslint'); + +const baseConfig = require('.'); +const whitespaceRules = require('./whitespaceRules'); + +const severities = ['off', 'warn', 'error']; + +function getSeverity(ruleConfig) { + if (isArray(ruleConfig)) { + return getSeverity(ruleConfig[0]); + } + if (typeof ruleConfig === 'number') { + return severities[ruleConfig]; + } + return ruleConfig; +} + +async function onlyErrorOnRules(rulesToError, config) { + const errorsOnly = { ...config }; + const cli = new ESLint({ + useEslintrc: false, + baseConfig: config + }); + const baseRules = (await cli.calculateConfigForFile(require.resolve('./'))).rules; + + entries(baseRules).forEach((rule) => { + const ruleName = rule[0]; + const ruleConfig = rule[1]; + const severity = getSeverity(ruleConfig); + + if (rulesToError.indexOf(ruleName) === -1 && severity === 'error') { + if (isArray(ruleConfig)) { + errorsOnly.rules[ruleName] = ['warn'].concat(ruleConfig.slice(1)); + } else if (typeof ruleConfig === 'number') { + errorsOnly.rules[ruleName] = 1; + } else { + errorsOnly.rules[ruleName] = 'warn'; + } + } + }); + + return errorsOnly; +} + +onlyErrorOnRules(whitespaceRules, baseConfig).then((config) => console.log(JSON.stringify(config))); diff --git a/packages/eslint-config-airbnb-base/whitespace.js b/packages/eslint-config-airbnb-base/whitespace.js new file mode 100644 index 0000000000..01e5198671 --- /dev/null +++ b/packages/eslint-config-airbnb-base/whitespace.js @@ -0,0 +1,61 @@ +/* eslint global-require: 0 */ + +const { isArray } = Array; +const { entries } = Object; +const { CLIEngine } = require('eslint'); + +if (CLIEngine) { + /* eslint no-inner-declarations: 0 */ + const whitespaceRules = require('./whitespaceRules'); + + const baseConfig = require('.'); + + const severities = ['off', 'warn', 'error']; + + function getSeverity(ruleConfig) { + if (isArray(ruleConfig)) { + return getSeverity(ruleConfig[0]); + } + if (typeof ruleConfig === 'number') { + return severities[ruleConfig]; + } + return ruleConfig; + } + + function onlyErrorOnRules(rulesToError, config) { + const errorsOnly = { ...config }; + const cli = new CLIEngine({ baseConfig: config, useEslintrc: false }); + const baseRules = cli.getConfigForFile(require.resolve('./')).rules; + + entries(baseRules).forEach((rule) => { + const ruleName = rule[0]; + const ruleConfig = rule[1]; + const severity = getSeverity(ruleConfig); + + if (rulesToError.indexOf(ruleName) === -1 && severity === 'error') { + if (isArray(ruleConfig)) { + errorsOnly.rules[ruleName] = ['warn'].concat(ruleConfig.slice(1)); + } else if (typeof ruleConfig === 'number') { + errorsOnly.rules[ruleName] = 1; + } else { + errorsOnly.rules[ruleName] = 'warn'; + } + } + }); + + return errorsOnly; + } + + module.exports = onlyErrorOnRules(whitespaceRules, baseConfig); +} else { + const path = require('path'); + const { execSync } = require('child_process'); + + // NOTE: ESLint adds runtime statistics to the output (so it's no longer JSON) if TIMING is set + module.exports = JSON.parse(String(execSync(path.join(__dirname, 'whitespace-async.js'), { + env: { + ...process.env, + TIMING: undefined, + } + }))); +} diff --git a/packages/eslint-config-airbnb-base/whitespaceRules.js b/packages/eslint-config-airbnb-base/whitespaceRules.js new file mode 100644 index 0000000000..6b0d3bfec7 --- /dev/null +++ b/packages/eslint-config-airbnb-base/whitespaceRules.js @@ -0,0 +1,49 @@ +module.exports = [ + 'array-bracket-newline', + 'array-bracket-spacing', + 'array-element-newline', + 'arrow-spacing', + 'block-spacing', + 'comma-spacing', + 'computed-property-spacing', + 'dot-location', + 'eol-last', + 'func-call-spacing', + 'function-paren-newline', + 'generator-star-spacing', + 'implicit-arrow-linebreak', + 'indent', + 'key-spacing', + 'keyword-spacing', + 'line-comment-position', + 'linebreak-style', + 'multiline-ternary', + 'newline-per-chained-call', + 'no-irregular-whitespace', + 'no-mixed-spaces-and-tabs', + 'no-multi-spaces', + 'no-regex-spaces', + 'no-spaced-func', + 'no-trailing-spaces', + 'no-whitespace-before-property', + 'nonblock-statement-body-position', + 'object-curly-newline', + 'object-curly-spacing', + 'object-property-newline', + 'one-var-declaration-per-line', + 'operator-linebreak', + 'padded-blocks', + 'padding-line-between-statements', + 'rest-spread-spacing', + 'semi-spacing', + 'semi-style', + 'space-before-blocks', + 'space-before-function-paren', + 'space-in-parens', + 'space-infix-ops', + 'space-unary-ops', + 'spaced-comment', + 'switch-colon-spacing', + 'template-tag-spacing', + 'import/newline-after-import' +]; diff --git a/packages/eslint-config-airbnb/.babelrc b/packages/eslint-config-airbnb/.babelrc new file mode 100644 index 0000000000..e0aceaae1c --- /dev/null +++ b/packages/eslint-config-airbnb/.babelrc @@ -0,0 +1,3 @@ +{ + "presets": ["airbnb"] +} diff --git a/packages/eslint-config-airbnb/.editorconfig b/packages/eslint-config-airbnb/.editorconfig new file mode 120000 index 0000000000..1b3ce07def --- /dev/null +++ b/packages/eslint-config-airbnb/.editorconfig @@ -0,0 +1 @@ +../../.editorconfig \ No newline at end of file diff --git a/packages/eslint-config-airbnb/.eslintrc b/packages/eslint-config-airbnb/.eslintrc new file mode 100644 index 0000000000..ab2c306fd9 --- /dev/null +++ b/packages/eslint-config-airbnb/.eslintrc @@ -0,0 +1,8 @@ +{ + "extends": "./index.js", + "rules": { + // disable requiring trailing commas because it might be nice to revert to + // being JSON at some point, and I don't want to make big changes now. + "comma-dangle": 0, + }, +} diff --git a/packages/eslint-config-airbnb/.npmrc b/packages/eslint-config-airbnb/.npmrc new file mode 120000 index 0000000000..cba44bb384 --- /dev/null +++ b/packages/eslint-config-airbnb/.npmrc @@ -0,0 +1 @@ +../../.npmrc \ No newline at end of file diff --git a/packages/eslint-config-airbnb/CHANGELOG.md b/packages/eslint-config-airbnb/CHANGELOG.md new file mode 100644 index 0000000000..68ba86b925 --- /dev/null +++ b/packages/eslint-config-airbnb/CHANGELOG.md @@ -0,0 +1,477 @@ +19.0.4 / 2021-12-25 +================== + - republish to fix #2529 + +19.0.3 / 2021-12-24 +================== + - [patch] set `namedComponents` option to match style guide + - [deps] update `eslint-plugin-react` + +19.0.2 / 2021-12-02 +================== + - [meta] fix "exports" path (#2525) + - [Tests] re-enable tests disabled for the eslint 8 upgrade + +19.0.1 / 2021-11-22 +================== + - [fix] `whitespace`: update to support eslint 8 (#2517) + - [deps] update `eslint-plugin-react` + - [dev deps] update `tape` + +19.0.0 / 2021-11-10 +================== + - [breaking] support `eslint` 8; drop `eslint` < 7 + - [patch] Explain why `react/jsx-key` is turned off (#2474) + - [fix] bump eslint-plugin-react-hooks peer dependency version (#2356) + - [patch] Alphabetize the rules for react-a11y.js (#2407) + - [Docs] HTTP => HTTPS (#2489) + - [readme] clarify hooks requirement (#2482) + - [deps] update `eslint-config-airbnb-base`, `eslint-plugin-jsx-a11y`, `eslint-plugin-react`, `eslint-plugin-react-hooks`, `safe-publish-latest`, `eslint-plugin-import`, `object.entries` + - [meta] add `--no-save` to link scripts + - [meta] use `prepublishOnly` script for npm 7+ + - [dev deps] update `@babel/runtime`, `tape` + +18.2.1 / 2020-11-06 +================== + - [patch] remove deprecated `jsx-a11y/accessible-emoji` rule (#2322) + - [patch] Fix ignoreNonDOM typo in jsx-a11y/aria-role rule (#2318) + - [patch] Fixed `handle` and `on` ordering in `sort-comp` rule (#2287) + - [deps] update `eslint-plugin-jsx-a11y`, `eslint-plugin-react` + - [deps] update `eslint-config-airbnb-base`, `object.assign` + - [dev deps] update `@babel/runtime`, `eslint-find-rules`, `eslint-plugin-import`, `eslint-plugin-jsx-a11y`, `eslint-plugin-react` + +18.2.0 / 2020-06-18 +================== + - [new] add `eslint` `v7` (#2240) + - [minor] Allow using `eslint-plugin-react-hooks` v3 and v4 (#2235, #2207) + - [minor] Fix typo in no-multiple-empty-lines rule (#2168) + - [patch] set `explicitSpread` to ignore for `react/jsx-props-no-spreading` (#2237) + - [patch] relax `eslint-plugin-react-hooks` down to v2.3, due to a controversial change in v2.5 + - [readme] fix typo (#2194) + - [deps] update `eslint-config-airbnb-base`, `eslint-plugin-jsx-a11y`, `eslint-plugin-import`, `eslint-plugin-react`, `babel-preset-airbnb`, `eslint-find-rules`, `in-publish`, `tape`, `object.entries` + - [tests] fix for eslint 7 + +18.1.0 / 2020-03-12 +================== + - [minor] Support eslint-plugin-react-hooks@2 (#2090) + - [minor] add new disabled rules, update eslint + - [fix] `whitespace`: only set erroring rules to "warn" + - [patch] Remove duplicate `componentDidCatch` (#2108) + - [patch] Add `static-variables` to `sort-comp` rule (#2109) + - [readme] clarify hooks section in readme (#2074) + - [deps] update `eslint`, `eslint-plugin-react`, `eslint-plugin-react-hooks`, `eslint-config-airbnb-base`, `eslint-plugin-import`, `object.entries` + - [dev deps] update `@babel/runtime`, `babel-preset-airbnb`, `safe-publish-latest`, `tape` + - [tests] re-enable eslint rule `prefer-destructuring` internally (#2110) + - [tests] fix eslint errors from c66cfc3 (#2112) + +18.0.1 / 2019-08-13 +================== + - [patch] `react/state-in-constructor`: fix incorrect configuration + +18.0.0 / 2019-08-10 +================== + - [breaking] add eslint v6, drop eslint v4 + - [deps] [breaking] update `eslint-config-airbnb-base`, `eslint-plugin-react`, `eslint-find-rules`, `eslint-plugin-import` + - [breaking] Remove rules/strict from 'extends' (#1962) + - [breaking] set react version to "detect" + - [breaking] disable `label-has-for`; enable `control-has-associated-label` + - [breaking] enable `react/jsx-props-no-spreading` + - [breaking] enable `react/jsx-fragments` + - [minor] enable `react/static-property-placement` + - [minor] enable `react/state-in-constructor` + - [minor] enable `react/jsx-curly-newline` + - [react] Add missing/unsafe lifecycle methods to react/sort-comp rule (#2043) + - [react] add componentDidCatch to lifecycle for react/sort-comp (#2060) + - [react] add `react-hooks` plugin (#2022) + - [dev deps] update babel-related deps to latest + - [tests] only run tests in non-lint per-package travis job + - [tests] use `eclint` instead of `editorconfig-tools` + - [meta] add disabled config for new react and a11y rules + + +17.1.1 / 2019-07-01 +================== + - [patch] Turn off `react/no-multi-comp` (#2006) + - [patch] extend `no-underscore-dangle` to allow for redux dev tools in the main config instead (#1996) + - [meta] add disabled `jsx-fragments` rule + - [deps] update `eslint-config-airbnb-base`, `object.entries`, `eslint-plugin-import`, `eslint-plugin-react`, `eslint-plugin-jsx-a11y`, `babel-preset-airbnb`, `tape` (#2005, etc) + - [docs] correct JavaScript capitalization (#2046) + - [docs] fix docs for whitespace config (#1914, #1871) + - [readme] Improve eslint config setup instructions for yarn (#2001) + +17.1.0 / 2018-08-13 +================== +- [new] add eslint v5 support +- [minor] enable `label-has-associated-control` rule +- [patch] re-enabling `jsx-one-expression-per-line` allowing single children, ignore DOM components on `jsx-no-bind` +- [deps] update `eslint`, `eslint-config-airbnb-base`, `eslint-plugin-react`, `eslint-plugin-import`, `safe-publish-latest`, `eslint-plugin-jsx-a11y`, `eslint-find-rules` +- [docs] fix readme typo (#1855) + +17.0.0 / 2018-06-21 +================== +- [breaking] update `eslint-config-airbnb-base` to v13 +- [breaking] enable `no-useless-path-segments` (#1743) +- [breaking] update `eslint-plugin-react` to `v7.6`; update rule configs (#1737) +- [breaking] bump react pragma to v16; update `class-methods-use-this`'s `exceptMethods` to include `componentDidCatch` (#1704) +- [new] Adds config entry point with only whitespace rules enabled (#1749, #1751) +- [patch] set `forbid-foreign-prop-types` to "warn" +- [patch] Add new methods introduced in react@16.3 (#1831) +- [patch] `label-has-for`: Remove redundant component (#1802) +- [patch] Add 'to' as a specialLink to the 'anchor-is-valid' a11y rule (#1648) +- [patch] disable `no-did-mount-set-state`, since it’s necessary for server-rendering. +- [deps] update `eslint`, `eslint-plugin-react`, `eslint-plugin-import`, +- [dev deps] update `babel-preset-airbnb`, `tape`, `eslint-find-rules` +- [meta] add ES2015-2018 in npm package keywords (#1587) +- [meta] Add licenses to sub packages (#1746) +- [docs] add `npx` shortcut (#1694) +- [docs] Use HTTPS for links to ESLint documentation (#1628) + +16.1.0 / 2017-10-16 +================== +- [deps] update `eslint-config-airbnb-base`, `eslint` to v4.9 + +16.0.0 / 2017-10-06 +================== +- [breaking] [deps] require `eslint` `v4`, update `eslint-config-airbnb-base` +- [breaking] [deps] Upgrade `eslint-plugin-jsx-a11y` to `v6`; enable more a11y rules (#1482) +- [breaking] enable/add react rules: `react/jsx-curly-brace-presence`, `react/no-typos`, `react/no-unused-state`, `react/no-redundant-should-component-update`, `react/default-props-match-prop-types` +- [new] add `propWrapperFunctions` default settings for `eslint-plugin-react` +- [new] Enable `react/jsx-closing-tag-location` (#1533) +- [deps] update `eslint` v4, `eslint-plugin-react`, `tape` +- [docs] Specify yarn-specific install instructions (#1511) + +15.1.0 / 2017-07-24 +================== +- [deps] allow eslint v3 or v4 (#1447) +- [deps] update `eslint-plugin-import`, `eslint-config-airbnb-base` + +15.0.2 / 2017-07-04 +================== +- [fix] jsx should be enabled via parserOptions, not via a root ecmaFeatures +- [deps] update `babel-preset-airbnb`, `eslint-find-rules`, `eslint-plugin-import`, `eslint-plugin-jsx-a11y`, `eslint-plugin-react`, `tape` + +15.0.1 / 2017-05-15 +================== +- [fix] set default React version to 15.0 (#1415) + +15.0.0 / 2017-05-14 +================== +- [breaking] set default React version to 0.15 +- [breaking] `update eslint-plugin-jsx-a11y` to v5, enable new rules +- [breaking] `update eslint-plugin-react` to v7, enable new rules +- [minor] enable rules: `jsx-max-props-per-line`, `void-dom-elements-no-children` +- [patch] Turn `ignorePureComponents` option on for react/prefer-stateless-function (#1378, #1398) +- [deps] update `eslint`, `eslint-plugin-react`, `eslint-config-airbnb-base` + +14.1.0 / 2017-02-05 +================== +- [patch] allow `eslint-plugin-jsx-a11y` to be v3 or v4. Remove `no-marquee` rule temporarily. +- [deps] update `eslint-config-airbnb-base`, `babel-preset-airbnb`, `eslint` + +14.0.0 / 2017-01-08 +================== +- [breaking] enable `react/no-array-index-key`, `react/require-default-props` +- [breaking] [deps] update `eslint`, `eslint-plugin-import`, `eslint-plugin-react`, `eslint-config-airbnb-base` +- [breaking] [deps] update `eslint-plugin-jsx-a11y` to v3 (#1166) +- [docs] add note about `install-peerdeps` (#1234) +- [docs] Updated instructions to support non-bash users (#1214) + +13.0.0 / 2016-11-06 +================== +- [breaking] Enable `import/no-webpack-loader-syntax` rule (#1123) +- [patch] `class-methods-use-this`: exempt React `getChildContext` (#1094) +- [patch] set `react/no-unused-prop-types` skipShapeProps (#1099) +- [deps] [breaking] update `eslint`, `eslint-config-airbnb-base`, `eslint-plugin-jsx-a11y`, `eslint-plugin-react`, `eslint-plugin-import` +- [dev deps] update `babel-preset-airbnb`, `eslint`, `eslint-find-rules`, `tape`, `safe-publish-latest` +- [Tests] on `node` `v7` +- [docs] ensure latest version of config is installed (#1121) + +12.0.0 / 2016-09-24 +================== +- [breaking] Enable react rules: `react/no-unescaped-entities`, `react/no-children-prop` +- [breaking] [deps] update `eslint-config-airbnb-base` +- [patch] disable deprecated and redundant `react/require-extension` rule (#978) + +11.2.0 / 2016-09-23 +================== +- [new] set `ecmaVersion` to 2017; enable object rest/spread; update `babel-preset-airbnb` +- [deps] update `eslint`, `eslint-config-airbnb-base`, `eslint-plugin-import`, `eslint-plugin-jsx-a11y`, `eslint-plugin-react`, `eslint-find-rules`, `safe-publish-latest` + +11.1.0 / 2016-09-11 +================== +- [deps] update `eslint-config-airbnb-base`, `eslint` + +11.0.0 / 2016-09-08 +================== +- [breaking] enable `react` rules: `react/no-danger-with-children`, `react/no-unused-prop-types`, `react/style-prop-object`, `react/forbid-prop-types`, `react/jsx-no-duplicate-props`; set `react/no-danger` to “warn” +- [breaking] enable `jsx-a11y` rules: `jsx-a11y/anchor-has-content`, `jsx-a11y/tabindex-no-positive`, `jsx-a11y/no-static-element-interactions` +- [deps] update `eslint`, `eslint-plugin-react`, `eslint-config-airbnb-base`, `eslint-find-rules`, `eslint-plugin-import`, `eslint-plugin-jsx-a11y` +- [patch] set `ignoreCase` to `true` in disabled rules. +- [docs] use “#” in example command rather than version numbers (#984) + +10.0.1 / 2016-08-12 +================== +- [deps] update `eslint`, `eslint-find-rules`, `eslint-plugin-jsx-a11y`, `eslint-plugin-import`, `eslint-config-airbnb-base` + +10.0.0 / 2016-08-01 +================== +- [breaking] enable jsx-a11y rules: + - `jsx-a11y/heading-has-content` + - `jsx-a11y/html-has-lang` + - `jsx-a11y/lang` + - `jsx-a11y/no-marquee` + - `jsx-a11y/scope` + - `jsx-a11y/href-no-hash` + - `jsx-a11y/label-has-for` +- [breaking] enable aria rules: + - `jsx-a11y/aria-props` + - `jsx-a11y/aria-proptypes` + - `jsx-a11y/aria-unsupported-elements` + - `jsx-a11y/role-has-required-aria-props` + - `jsx-a11y/role-supports-aria-props` +- [breaking] enable react rules: + - `react/jsx-filename-extension` + - `react/jsx-no-comment-textnodes` + - `react/jsx-no-target-blank` + - `react/require-extension` + - `react/no-render-return-value` + - `react/no-find-dom-node` + - `react/no-deprecated` +- [deps] [breaking] update `eslint` to v3, `eslint-config-airbnb-base` to v5, `eslint-find-rules`, `eslint-plugin-import`, `eslint-plugin-jsx-a11y` to v2, `eslint-plugin-react` to v6, `tape`. drop node < 4 support. +- [deps] update `eslint-config-airbnb-base`, `eslint-plugin-react`, `eslint-plugin-import`, `eslint-plugin-jsx-a11y`, `babel-tape-runner`, add `babel-preset-airbnb`. ensure react is `>=` 0.13.0 +- [patch] loosen `jsx-pascal-case` rule to allow all caps component names +- [tests] stop testing < node 4 +- [tests] use `in-publish` because coffeescript screwed up the prepublish script for everyone +- [tests] Only run `eslint-find-rules` on prepublish, not in tests +- [tests] Even though the base config may not be up to date in the main package, let’s `npm link` the base package into the main one for the sake of travis-ci tests +- [docs] update the peer dep install command to dynamically look up the right version numbers when installing peer deps +- add `safe-publish-latest` to `prepublish` + +9.0.1 / 2016-05-08 +================== +- [patch] update `eslint-config-airbnb-base` to v3.0.1 + +9.0.0 / 2016-05-07 +================== +- [breaking] update `eslint-config-airbnb-base` to v3 +- [deps] update `eslint-find-rules`, `eslint-plugin-import`, `eslint-plugin-jsx-a11y` + +8.0.0 / 2016-04-21 +================== +- [breaking] Migrate non-React rules to a separate linter config (`eslint-config-airbnb-base`) +- [breaking] disallow empty methods +- [breaking] disallow empty restructuring patterns +- [breaking] enable `no-restricted-syntax` rule +- [breaking] enable `global-require` rule +- [breaking] [react] enable `react/jsx-curly-spacing` rule ([#693](https://github.com/airbnb/javascript/issues/693)) +- [semver-minor] [react] Add `react/jsx-first-prop-new-line` rule +- [semver-minor] [react] enable `jsx-equals-spacing` rule +- [semver-minor] [react] enable `jsx-indent` rule +- [semver-minor] enforce spacing inside single-line blocks +- [semver-minor] enforce `no-underscore-dangle` +- [semver-minor] Enable import/no-unresolved and import/export rules ([#825](https://github.com/airbnb/javascript/issues/825)) +- [semver-patch] Enable `no-useless-concat` rule which `prefer-template` already covers +- [semver-patch] Allow `== null` ([#542](https://github.com/airbnb/javascript/issues/542)) +- [dev deps / peer deps] update `eslint`, `eslint-plugin-react`, `eslint-plugin-import` +- [dev deps / peer deps] update `eslint-plugin-jsx-a11y` and rename rules ([#838](https://github.com/airbnb/javascript/issues/838)) +- [refactor] [react] separate a11y rules to their own file +- [refactor] Add missing disabled rules. +- [tests] Add `eslint-find-rules` to prevent missing rules + +7.0.0 / 2016-04-11 +================== +- [react] [breaking] Add accessibility rules to the React style guide + `eslint-plugin-a11y` +- [breaking] enable `react/require-render-return` +- [breaking] Add `no-dupe-class-members` rule + section ([#785](https://github.com/airbnb/javascript/issues/785)) +- [breaking] error on debugger statements +- [breaking] add `no-useless-escape` rule +- [breaking] add `no-duplicate-imports` rule +- [semver-minor] enable `jsx-pascal-case` rule +- [deps] update `eslint`, `react` +- [dev deps] update `eslint`, `eslint-plugin-react` + +6.2.0 / 2016-03-22 +================== +- [new] Allow arrow functions in JSX props +- [fix] re-enable `no-confusing-arrow` rule, with `allowParens` option enabled ([#752](https://github.com/airbnb/javascript/issues/752), [#791](https://github.com/airbnb/javascript/issues/791)) +- [dev deps] update `tape`, `eslint`, `eslint-plugin-react` +- [peer deps] update `eslint`, `eslint-plugin-react` + +6.1.0 / 2016-02-22 +================== +- [new] enable [`react/prefer-stateless-function`][react/prefer-stateless-function] +- [dev deps] update `react-plugin-eslint`, `eslint`, `tape` + +6.0.2 / 2016-02-22 +================== +- [fix] disable [`no-confusing-arrow`][no-confusing-arrow] due to an `eslint` bug ([#752](https://github.com/airbnb/javascript/issues/752)) + +6.0.1 / 2016-02-21 +================== +- [fix] disable [`newline-per-chained-call`][newline-per-chained-call] due to an `eslint` bug ([#748](https://github.com/airbnb/javascript/issues/748)) + +6.0.0 / 2016-02-21 +================== +- [breaking] enable [`array-callback-return`][array-callback-return] +- [breaking] enable [`no-confusing-arrow`][no-confusing-arrow] +- [breaking] enable [`no-new-symbol`][no-new-symbol] +- [breaking] enable [`no-restricted-imports`][no-restricted-imports] +- [breaking] enable [`no-useless-constructor`][no-useless-constructor] +- [breaking] enable [`prefer-rest-params`][prefer-rest-params] +- [breaking] enable [`template-curly-spacing`][template-curly-spacing] +- [breaking] enable [`newline-per-chained-call`][newline-per-chained-call] +- [breaking] enable [`one-var-declaration-per-line`][one-var-declaration-per-line] +- [breaking] enable [`no-self-assign`][no-self-assign] +- [breaking] enable [`no-whitespace-before-property`][no-whitespace-before-property] +- [breaking] [react] enable [`react/jsx-space-before-closing`][react/jsx-space-before-closing] +- [breaking] [react] enable `static-methods` at top of [`react/sort-comp`][react/sort-comp] +- [breaking] [react] don't `ignoreTranspilerName` for [`react/display-name`][react/display-name] +- [peer+dev deps] update `eslint`, `eslint-plugin-react` ([#730](https://github.com/airbnb/javascript/issues/730)) + +5.0.1 / 2016-02-13 +================== +- [fix] `eslint` peerDep should not include breaking changes + +5.0.0 / 2016-02-03 +================== +- [breaking] disallow unneeded ternary expressions +- [breaking] Avoid lexical declarations in case/default clauses +- [dev deps] update `babel-tape-runner`, `eslint-plugin-react`, `react`, `tape` + +4.0.0 / 2016-01-22 +================== +- [breaking] require outer IIFE wrapping; flesh out guide section +- [minor] Add missing [`arrow-body-style`][arrow-body-style], [`prefer-template`][prefer-template] rules ([#678](https://github.com/airbnb/javascript/issues/678)) +- [minor] Add [`prefer-arrow-callback`][prefer-arrow-callback] to ES6 rules (to match the guide) ([#677](https://github.com/airbnb/javascript/issues/677)) +- [Tests] run `npm run lint` as part of tests; fix errors +- [Tests] use `parallelshell` to parallelize npm run-scripts + +3.1.0 / 2016-01-07 +================== +- [minor] Allow multiple stateless components in a single file + +3.0.2 / 2016-01-06 +================== +- [fix] Ignore URLs in [`max-len`][max-len] ([#664](https://github.com/airbnb/javascript/issues/664)) + +3.0.1 / 2016-01-06 +================== +- [fix] because we use babel, keywords should not be quoted + +3.0.0 / 2016-01-04 +================== +- [breaking] enable [`quote-props`][quote-props] rule ([#632](https://github.com/airbnb/javascript/issues/632)) +- [breaking] Define a max line length of 100 characters ([#639](https://github.com/airbnb/javascript/issues/639)) +- [breaking] [react] Minor cleanup for the React styleguide, add [`react/jsx-no-bind`][react/jsx-no-bind] ([#619](https://github.com/airbnb/javascript/issues/619)) +- [breaking] update best-practices config to prevent parameter object manipulation ([#627](https://github.com/airbnb/javascript/issues/627)) +- [minor] Enable [`react/no-is-mounted`][react/no-is-mounted] rule (#635, #633) +- [minor] Sort [`react/prefer-es6-class`][react/prefer-es6-class] alphabetically ([#634](https://github.com/airbnb/javascript/issues/634)) +- [minor] enable [`react/prefer-es6-class`][react/prefer-es6-class] rule +- Permit strict mode in "legacy" config +- [react] add missing rules from `eslint-plugin-react` (enforcing where necessary) ([#581](https://github.com/airbnb/javascript/issues/581)) +- [dev deps] update `eslint-plugin-react` + +2.1.1 / 2015-12-15 +================== +- [fix] Remove deprecated [`react/jsx-quotes`][react/jsx-quotes] ([#622](https://github.com/airbnb/javascript/issues/622)) + +2.1.0 / 2015-12-15 +================== +- [fix] use `require.resolve` to allow nested `extend`s ([#582](https://github.com/airbnb/javascript/issues/582)) +- [new] enable [`object-shorthand`][object-shorthand] rule ([#621](https://github.com/airbnb/javascript/issues/621)) +- [new] enable [`arrow-spacing`][arrow-spacing] rule ([#517](https://github.com/airbnb/javascript/issues/517)) +- [docs] flesh out react rule defaults ([#618](https://github.com/airbnb/javascript/issues/618)) + +2.0.0 / 2015-12-03 +================== +- [breaking] [`space-before-function-paren`][space-before-function-paren]: require function spacing: `function (` ([#605](https://github.com/airbnb/javascript/issues/605)) +- [breaking] [`indent`][indent]: Fix switch statement indentation rule ([#606](https://github.com/airbnb/javascript/issues/606)) +- [breaking] [`array-bracket-spacing`][array-bracket-spacing], [`computed-property-spacing`][computed-property-spacing]: disallow spacing inside brackets ([#594](https://github.com/airbnb/javascript/issues/594)) +- [breaking] [`object-curly-spacing`][object-curly-spacing]: require padding inside curly braces ([#594](https://github.com/airbnb/javascript/issues/594)) +- [breaking] [`space-in-parens`][space-in-parens]: disallow spaces in parens ([#594](https://github.com/airbnb/javascript/issues/594)) + +1.0.2 / 2015-11-25 +================== +- [breaking] [`no-multiple-empty-lines`][no-multiple-empty-lines]: only allow 1 blank line at EOF ([#578](https://github.com/airbnb/javascript/issues/578)) +- [new] `restParams`: enable rest params ([#592](https://github.com/airbnb/javascript/issues/592)) + +1.0.1 / 2015-11-25 +================== +- *erroneous publish* + +1.0.0 / 2015-11-08 +================== +- require `eslint` `v1.0.0` or higher +- remove `babel-eslint` dependency + +0.1.1 / 2015-11-05 +================== +- remove [`id-length`][id-length] rule ([#569](https://github.com/airbnb/javascript/issues/569)) +- enable [`no-mixed-spaces-and-tabs`][no-mixed-spaces-and-tabs] ([#539](https://github.com/airbnb/javascript/issues/539)) +- enable [`no-const-assign`][no-const-assign] ([#560](https://github.com/airbnb/javascript/issues/560)) +- enable [`space-before-keywords`][space-before-keywords] ([#554](https://github.com/airbnb/javascript/issues/554)) + +0.1.0 / 2015-11-05 +================== +- switch to modular rules files courtesy the [eslint-config-default][ecd] project and [@taion][taion]. [PR][pr-modular] +- export `eslint-config-airbnb/legacy` for ES5-only users. `eslint-config-airbnb/legacy` does not require the `babel-eslint` parser. [PR][pr-legacy] + +0.0.9 / 2015-09-24 +================== +- add rule [`no-undef`][no-undef] +- add rule [`id-length`][id-length] + +0.0.8 / 2015-08-21 +================== +- now has a changelog +- now is modular (see instructions above for with react and without react versions) + +0.0.7 / 2015-07-30 +================== +- TODO: fill in + + +[ecd]: https://github.com/walmartlabs/eslint-config-defaults +[taion]: https://github.com/taion +[pr-modular]: https://github.com/airbnb/javascript/pull/526 +[pr-legacy]: https://github.com/airbnb/javascript/pull/527 + +[array-bracket-spacing]: https://eslint.org/docs/rules/array-bracket-spacing +[array-callback-return]: https://eslint.org/docs/rules/array-callback-return +[arrow-body-style]: https://eslint.org/docs/rules/arrow-body-style +[arrow-spacing]: https://eslint.org/docs/rules/arrow-spacing +[computed-property-spacing]: https://eslint.org/docs/rules/computed-property-spacing +[id-length]: https://eslint.org/docs/rules/id-length +[indent]: https://eslint.org/docs/rules/indent +[max-len]: https://eslint.org/docs/rules/max-len +[newline-per-chained-call]: https://eslint.org/docs/rules/newline-per-chained-call +[no-confusing-arrow]: https://eslint.org/docs/rules/no-confusing-arrow +[no-const-assign]: https://eslint.org/docs/rules/no-const-assign +[no-mixed-spaces-and-tabs]: https://eslint.org/docs/rules/no-mixed-spaces-and-tabs +[no-multiple-empty-lines]: https://eslint.org/docs/rules/no-multiple-empty-lines +[no-new-symbol]: https://eslint.org/docs/rules/no-new-symbol +[no-restricted-imports]: https://eslint.org/docs/rules/no-restricted-imports +[no-self-assign]: https://eslint.org/docs/rules/no-self-assign +[no-undef]: https://eslint.org/docs/rules/no-undef +[no-useless-constructor]: https://eslint.org/docs/rules/no-useless-constructor +[no-whitespace-before-property]: https://eslint.org/docs/rules/no-whitespace-before-property +[object-curly-spacing]: https://eslint.org/docs/rules/object-curly-spacing +[object-shorthand]: https://eslint.org/docs/rules/object-shorthand +[one-var-declaration-per-line]: https://eslint.org/docs/rules/one-var-declaration-per-line +[prefer-arrow-callback]: https://eslint.org/docs/rules/prefer-arrow-callback +[prefer-rest-params]: https://eslint.org/docs/rules/prefer-rest-params +[prefer-template]: https://eslint.org/docs/rules/prefer-template +[quote-props]: https://eslint.org/docs/rules/quote-props +[space-before-function-paren]: https://eslint.org/docs/rules/space-before-function-paren +[space-before-keywords]: https://eslint.org/docs/rules/space-before-keywords +[space-in-parens]: https://eslint.org/docs/rules/space-in-parens +[template-curly-spacing]: https://eslint.org/docs/rules/template-curly-spacing + +[react/jsx-space-before-closing]: https://github.com/jsx-eslint/eslint-plugin-react/blob/HEAD/docs/rules/jsx-space-before-closing.md +[react/sort-comp]: https://github.com/jsx-eslint/eslint-plugin-react/blob/HEAD/docs/rules/sort-comp.md +[react/display-name]: https://github.com/jsx-eslint/eslint-plugin-react/blob/HEAD/docs/rules/display-name.md +[react/jsx-no-bind]: https://github.com/jsx-eslint/eslint-plugin-react/blob/HEAD/docs/rules/jsx-no-bind.md +[react/no-is-mounted]: https://github.com/jsx-eslint/eslint-plugin-react/blob/HEAD/docs/rules/no-is-mounted.md +[react/prefer-es6-class]: https://github.com/jsx-eslint/eslint-plugin-react/blob/HEAD/docs/rules/prefer-es6-class.md +[react/jsx-quotes]: https://github.com/jsx-eslint/eslint-plugin-react/blob/f817e37beddddc84b4788969f07c524fa7f0823b/docs/rules/jsx-quotes.md +[react/prefer-stateless-function]: https://github.com/jsx-eslint/eslint-plugin-react/blob/HEAD/docs/rules/prefer-stateless-function.md diff --git a/packages/eslint-config-airbnb/LICENSE.md b/packages/eslint-config-airbnb/LICENSE.md new file mode 100644 index 0000000000..69d80c0252 --- /dev/null +++ b/packages/eslint-config-airbnb/LICENSE.md @@ -0,0 +1,21 @@ +MIT License + +Copyright (c) 2012 Airbnb + +Permission is hereby granted, free of charge, to any person obtaining a copy +of this software and associated documentation files (the "Software"), to deal +in the Software without restriction, including without limitation the rights +to use, copy, modify, merge, publish, distribute, sublicense, and/or sell +copies of the Software, and to permit persons to whom the Software is +furnished to do so, subject to the following conditions: + +The above copyright notice and this permission notice shall be included in all +copies or substantial portions of the Software. + +THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR +IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, +FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE +AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER +LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, +OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE +SOFTWARE. diff --git a/packages/eslint-config-airbnb/README.md b/packages/eslint-config-airbnb/README.md new file mode 100644 index 0000000000..3b3f43196d --- /dev/null +++ b/packages/eslint-config-airbnb/README.md @@ -0,0 +1,87 @@ +# eslint-config-airbnb + +[![npm version](https://badge.fury.io/js/eslint-config-airbnb.svg)](https://badge.fury.io/js/eslint-config-airbnb) + +This package provides Airbnb's .eslintrc as an extensible shared config. + +## Usage + +We export three ESLint configurations for your usage. + +### eslint-config-airbnb + +Our default export contains most of our ESLint rules, including ECMAScript 6+ and React. It requires `eslint`, `eslint-plugin-import`, `eslint-plugin-react`, `eslint-plugin-react-hooks`, and `eslint-plugin-jsx-a11y`. Note that it does not enable our React Hooks rules. To enable those, see the [`eslint-config-airbnb/hooks` section](#eslint-config-airbnbhooks). + +If you don't need React, see [eslint-config-airbnb-base](https://npmjs.com/eslint-config-airbnb-base). + +1. Install the correct versions of each package, which are listed by the command: + + ```sh + npm info "eslint-config-airbnb@latest" peerDependencies + ``` + + If using **npm 5+**, use this shortcut + + ```sh + npx install-peerdeps --dev eslint-config-airbnb + ``` + + If using **yarn**, you can also use the shortcut described above if you have npm 5+ installed on your machine, as the command will detect that you are using yarn and will act accordingly. + Otherwise, run `npm info "eslint-config-airbnb@latest" peerDependencies` to list the peer dependencies and versions, then run `yarn add --dev @` for each listed peer dependency. + + If using **npm < 5**, Linux/OSX users can run + + ```sh + ( + export PKG=eslint-config-airbnb; + npm info "$PKG@latest" peerDependencies --json | command sed 's/[\{\},]//g ; s/: /@/g' | xargs npm install --save-dev "$PKG@latest" + ) + ``` + + Which produces and runs a command like: + + ```sh + npm install --save-dev eslint-config-airbnb eslint@^#.#.# eslint-plugin-jsx-a11y@^#.#.# eslint-plugin-import@^#.#.# eslint-plugin-react@^#.#.# eslint-plugin-react-hooks@^#.#.# + ``` + + If using **npm < 5**, Windows users can either install all the peer dependencies manually, or use the [install-peerdeps](https://github.com/nathanhleung/install-peerdeps) cli tool. + + ```sh + npm install -g install-peerdeps + install-peerdeps --dev eslint-config-airbnb + ``` + The cli will produce and run a command like: + + ```sh + npm install --save-dev eslint-config-airbnb eslint@^#.#.# eslint-plugin-jsx-a11y@^#.#.# eslint-plugin-import@^#.#.# eslint-plugin-react@^#.#.# eslint-plugin-react-hooks@^#.#.# + ``` + +2. Add `"extends": "airbnb"` to your `.eslintrc` + +### eslint-config-airbnb/hooks + +This entry point enables the linting rules for React hooks (requires v16.8+). To use, add `"extends": ["airbnb", "airbnb/hooks"]` to your `.eslintrc`. + +### eslint-config-airbnb/whitespace + +This entry point only errors on whitespace rules and sets all other rules to warnings. View the list of whitespace rules [here](https://github.com/airbnb/javascript/blob/master/packages/eslint-config-airbnb/whitespace.js). + +### eslint-config-airbnb/base + +This entry point is deprecated. See [eslint-config-airbnb-base](https://npmjs.com/eslint-config-airbnb-base). + +### eslint-config-airbnb/legacy + +This entry point is deprecated. See [eslint-config-airbnb-base](https://npmjs.com/eslint-config-airbnb-base). + +See [Airbnb's JavaScript styleguide](https://github.com/airbnb/javascript) and +the [ESlint config docs](https://eslint.org/docs/user-guide/configuring#extending-configuration-files) +for more information. + +## Improving this config + +Consider adding test cases if you're making complicated rules changes, like anything involving regexes. Perhaps in a distant future, we could use literate programming to structure our README as test cases for our .eslintrc? + +You can run tests with `npm test`. + +You can make sure this module lints with itself using `npm run lint`. diff --git a/packages/eslint-config-airbnb/base.js b/packages/eslint-config-airbnb/base.js new file mode 100644 index 0000000000..bb1ea39118 --- /dev/null +++ b/packages/eslint-config-airbnb/base.js @@ -0,0 +1,4 @@ +module.exports = { + extends: ['eslint-config-airbnb-base'].map(require.resolve), + rules: {}, +}; diff --git a/packages/eslint-config-airbnb/hooks.js b/packages/eslint-config-airbnb/hooks.js new file mode 100644 index 0000000000..a7f70284e3 --- /dev/null +++ b/packages/eslint-config-airbnb/hooks.js @@ -0,0 +1,6 @@ +module.exports = { + extends: [ + './rules/react-hooks.js', + ].map(require.resolve), + rules: {} +}; diff --git a/packages/eslint-config-airbnb/index.js b/packages/eslint-config-airbnb/index.js new file mode 100644 index 0000000000..6432e10dda --- /dev/null +++ b/packages/eslint-config-airbnb/index.js @@ -0,0 +1,8 @@ +module.exports = { + extends: [ + 'eslint-config-airbnb-base', + './rules/react', + './rules/react-a11y', + ].map(require.resolve), + rules: {} +}; diff --git a/packages/eslint-config-airbnb/legacy.js b/packages/eslint-config-airbnb/legacy.js new file mode 100644 index 0000000000..e88f71224a --- /dev/null +++ b/packages/eslint-config-airbnb/legacy.js @@ -0,0 +1,4 @@ +module.exports = { + extends: ['eslint-config-airbnb-base/legacy'].map(require.resolve), + rules: {}, +}; diff --git a/packages/eslint-config-airbnb/package.json b/packages/eslint-config-airbnb/package.json new file mode 100644 index 0000000000..c36359ea7c --- /dev/null +++ b/packages/eslint-config-airbnb/package.json @@ -0,0 +1,97 @@ +{ + "name": "eslint-config-airbnb", + "version": "19.0.4", + "description": "Airbnb's ESLint config, following our styleguide", + "main": "index.js", + "exports": { + ".": "./index.js", + "./base": "./base.js", + "./hooks": "./hooks.js", + "./legacy": "./legacy.js", + "./whitespace": "./whitespace.js", + "./rules/react": "./rules/react.js", + "./rules/react-a11y": "./rules/react-a11y.js", + "./rules/react-hooks": "./rules/react-hooks.js", + "./package.json": "./package.json" + }, + "scripts": { + "prelint": "eclint check $(git ls-files | xargs find 2> /dev/null | grep -vE 'node_modules|\\.git')", + "lint": "eslint .", + "pretests-only": "node ./test/requires", + "tests-only": "babel-tape-runner ./test/test-*.js", + "prepublishOnly": "eslint-find-rules --unused && npm test && safe-publish-latest", + "prepublish": "not-in-publish || npm run prepublishOnly", + "pretest": "npm run --silent lint", + "test": "npm run --silent tests-only", + "link:eslint": "cd node_modules/eslint && npm link --production && cd -", + "pretravis": "npm run link:eslint && cd ../eslint-config-airbnb-base && npm link --no-save eslint && npm install && npm link && cd - && npm link --no-save eslint-config-airbnb-base", + "travis": "npm run --silent tests-only", + "posttravis": "npm unlink --no-save eslint-config-airbnb-base eslint >/dev/null &" + }, + "repository": { + "type": "git", + "url": "https://github.com/airbnb/javascript" + }, + "keywords": [ + "eslint", + "eslintconfig", + "config", + "airbnb", + "javascript", + "styleguide", + "es2015", + "es2016", + "es2017", + "es2018" + ], + "author": "Jake Teton-Landis (https://twitter.com/@jitl)", + "contributors": [ + { + "name": "Jake Teton-Landis", + "url": "https://twitter.com/jitl" + }, + { + "name": "Jordan Harband", + "email": "ljharb@gmail.com", + "url": "http://ljharb.codes" + }, + { + "name": "Harrison Shoff", + "url": "https://twitter.com/hshoff" + } + ], + "license": "MIT", + "bugs": { + "url": "https://github.com/airbnb/javascript/issues" + }, + "homepage": "https://github.com/airbnb/javascript", + "dependencies": { + "eslint-config-airbnb-base": "^15.0.0" + }, + "devDependencies": { + "@babel/runtime": "^7.25.6", + "babel-preset-airbnb": "^4.5.0", + "babel-tape-runner": "^3.0.0", + "eclint": "^2.8.1", + "eslint": "^7.32.0 || ^8.2.0", + "eslint-find-rules": "^4.1.0", + "eslint-plugin-import": "^2.30.0", + "eslint-plugin-jsx-a11y": "^6.10.0", + "eslint-plugin-react": "^7.36.1", + "eslint-plugin-react-hooks": "^5.1.0", + "in-publish": "^2.0.1", + "react": ">= 0.13.0", + "safe-publish-latest": "^2.0.0", + "tape": "^5.9.0" + }, + "peerDependencies": { + "eslint": "^7.32.0 || ^8.2.0", + "eslint-plugin-import": "^2.30.0", + "eslint-plugin-jsx-a11y": "^6.10.0", + "eslint-plugin-react": "^7.36.1", + "eslint-plugin-react-hooks": "^5.1.0" + }, + "engines": { + "node": "^10.12.0 || ^12.22.0 || ^14.17.0 || >=16.0.0" + } +} diff --git a/packages/eslint-config-airbnb/rules/react-a11y.js b/packages/eslint-config-airbnb/rules/react-a11y.js new file mode 100644 index 0000000000..58065120a4 --- /dev/null +++ b/packages/eslint-config-airbnb/rules/react-a11y.js @@ -0,0 +1,269 @@ +module.exports = { + plugins: [ + 'jsx-a11y', + 'react' + ], + + parserOptions: { + ecmaFeatures: { + jsx: true, + }, + }, + + rules: { + // ensure emoji are accessible + // https://github.com/jsx-eslint/eslint-plugin-jsx-a11y/blob/master/docs/rules/accessible-emoji.md + // disabled; rule is deprecated + 'jsx-a11y/accessible-emoji': 'off', + + // Enforce that all elements that require alternative text have meaningful information + // https://github.com/jsx-eslint/eslint-plugin-jsx-a11y/blob/master/docs/rules/alt-text.md + 'jsx-a11y/alt-text': ['error', { + elements: ['img', 'object', 'area', 'input[type="image"]'], + img: [], + object: [], + area: [], + 'input[type="image"]': [], + }], + + // Enforce that anchors have content + // https://github.com/jsx-eslint/eslint-plugin-jsx-a11y/blob/master/docs/rules/anchor-has-content.md + 'jsx-a11y/anchor-has-content': ['error', { components: [] }], + + // ensure tags are valid + // https://github.com/jsx-eslint/eslint-plugin-jsx-a11y/blob/0745af376cdc8686d85a361ce36952b1fb1ccf6e/docs/rules/anchor-is-valid.md + 'jsx-a11y/anchor-is-valid': ['error', { + components: ['Link'], + specialLink: ['to'], + aspects: ['noHref', 'invalidHref', 'preferButton'], + }], + + // elements with aria-activedescendant must be tabbable + // https://github.com/jsx-eslint/eslint-plugin-jsx-a11y/blob/master/docs/rules/aria-activedescendant-has-tabindex.md + 'jsx-a11y/aria-activedescendant-has-tabindex': 'error', + + // Enforce all aria-* props are valid. + // https://github.com/jsx-eslint/eslint-plugin-jsx-a11y/blob/master/docs/rules/aria-props.md + 'jsx-a11y/aria-props': 'error', + + // Enforce ARIA state and property values are valid. + // https://github.com/jsx-eslint/eslint-plugin-jsx-a11y/blob/master/docs/rules/aria-proptypes.md + 'jsx-a11y/aria-proptypes': 'error', + + // Require ARIA roles to be valid and non-abstract + // https://github.com/jsx-eslint/eslint-plugin-jsx-a11y/blob/master/docs/rules/aria-role.md + 'jsx-a11y/aria-role': ['error', { ignoreNonDOM: false }], + + // Enforce that elements that do not support ARIA roles, states, and + // properties do not have those attributes. + // https://github.com/jsx-eslint/eslint-plugin-jsx-a11y/blob/master/docs/rules/aria-unsupported-elements.md + 'jsx-a11y/aria-unsupported-elements': 'error', + + // Ensure the autocomplete attribute is correct and suitable for the form field it is used with + // https://github.com/jsx-eslint/eslint-plugin-jsx-a11y/blob/29c68596b15c4ff0a40daae6d4a2670e36e37d35/docs/rules/autocomplete-valid.md + 'jsx-a11y/autocomplete-valid': ['off', { + inputComponents: [], + }], + + // require onClick be accompanied by onKeyUp/onKeyDown/onKeyPress + // https://github.com/jsx-eslint/eslint-plugin-jsx-a11y/blob/master/docs/rules/click-events-have-key-events.md + 'jsx-a11y/click-events-have-key-events': 'error', + + // Enforce that a control (an interactive element) has a text label. + // https://github.com/jsx-eslint/eslint-plugin-jsx-a11y/blob/master/docs/rules/control-has-associated-label.md + 'jsx-a11y/control-has-associated-label': ['error', { + labelAttributes: ['label'], + controlComponents: [], + ignoreElements: [ + 'audio', + 'canvas', + 'embed', + 'input', + 'textarea', + 'tr', + 'video', + ], + ignoreRoles: [ + 'grid', + 'listbox', + 'menu', + 'menubar', + 'radiogroup', + 'row', + 'tablist', + 'toolbar', + 'tree', + 'treegrid', + ], + depth: 5, + }], + + // ensure tags have content and are not aria-hidden + // https://github.com/jsx-eslint/eslint-plugin-jsx-a11y/blob/master/docs/rules/heading-has-content.md + 'jsx-a11y/heading-has-content': ['error', { components: [''] }], + + // require HTML elements to have a "lang" prop + // https://github.com/jsx-eslint/eslint-plugin-jsx-a11y/blob/master/docs/rules/html-has-lang.md + 'jsx-a11y/html-has-lang': 'error', + + // ensure iframe elements have a unique title + // https://github.com/jsx-eslint/eslint-plugin-jsx-a11y/blob/master/docs/rules/iframe-has-title.md + 'jsx-a11y/iframe-has-title': 'error', + + // Prevent img alt text from containing redundant words like "image", "picture", or "photo" + // https://github.com/jsx-eslint/eslint-plugin-jsx-a11y/blob/master/docs/rules/img-redundant-alt.md + 'jsx-a11y/img-redundant-alt': 'error', + + // Elements with an interactive role and interaction handlers must be focusable + // https://github.com/jsx-eslint/eslint-plugin-jsx-a11y/blob/master/docs/rules/interactive-supports-focus.md + 'jsx-a11y/interactive-supports-focus': 'error', + + // Enforce that a label tag has a text label and an associated control. + // https://github.com/jsx-eslint/eslint-plugin-jsx-a11y/blob/b800f40a2a69ad48015ae9226fbe879f946757ed/docs/rules/label-has-associated-control.md + 'jsx-a11y/label-has-associated-control': ['error', { + labelComponents: [], + labelAttributes: [], + controlComponents: [], + assert: 'both', + depth: 25 + }], + + // require HTML element's lang prop to be valid + // https://github.com/jsx-eslint/eslint-plugin-jsx-a11y/blob/master/docs/rules/lang.md + 'jsx-a11y/lang': 'error', + + // media elements must have captions + // https://github.com/jsx-eslint/eslint-plugin-jsx-a11y/blob/master/docs/rules/media-has-caption.md + 'jsx-a11y/media-has-caption': ['error', { + audio: [], + video: [], + track: [], + }], + + // require that mouseover/out come with focus/blur, for keyboard-only users + // https://github.com/jsx-eslint/eslint-plugin-jsx-a11y/blob/master/docs/rules/mouse-events-have-key-events.md + 'jsx-a11y/mouse-events-have-key-events': 'error', + + // Prevent use of `accessKey` + // https://github.com/jsx-eslint/eslint-plugin-jsx-a11y/blob/master/docs/rules/no-access-key.md + 'jsx-a11y/no-access-key': 'error', + + // prohibit autoFocus prop + // https://github.com/jsx-eslint/eslint-plugin-jsx-a11y/blob/master/docs/rules/no-autofocus.md + 'jsx-a11y/no-autofocus': ['error', { ignoreNonDOM: true }], + + // prevent distracting elements, like and + // https://github.com/jsx-eslint/eslint-plugin-jsx-a11y/blob/master/docs/rules/no-distracting-elements.md + 'jsx-a11y/no-distracting-elements': ['error', { + elements: ['marquee', 'blink'], + }], + + // WAI-ARIA roles should not be used to convert an interactive element to non-interactive + // https://github.com/jsx-eslint/eslint-plugin-jsx-a11y/blob/master/docs/rules/no-interactive-element-to-noninteractive-role.md + 'jsx-a11y/no-interactive-element-to-noninteractive-role': ['error', { + tr: ['none', 'presentation'], + }], + + // A non-interactive element does not support event handlers (mouse and key handlers) + // https://github.com/jsx-eslint/eslint-plugin-jsx-a11y/blob/master/docs/rules/no-noninteractive-element-interactions.md + 'jsx-a11y/no-noninteractive-element-interactions': ['error', { + handlers: [ + 'onClick', + 'onMouseDown', + 'onMouseUp', + 'onKeyPress', + 'onKeyDown', + 'onKeyUp', + ] + }], + + // WAI-ARIA roles should not be used to convert a non-interactive element to interactive + // https://github.com/jsx-eslint/eslint-plugin-jsx-a11y/blob/master/docs/rules/no-noninteractive-element-to-interactive-role.md + 'jsx-a11y/no-noninteractive-element-to-interactive-role': ['error', { + ul: ['listbox', 'menu', 'menubar', 'radiogroup', 'tablist', 'tree', 'treegrid'], + ol: ['listbox', 'menu', 'menubar', 'radiogroup', 'tablist', 'tree', 'treegrid'], + li: ['menuitem', 'option', 'row', 'tab', 'treeitem'], + table: ['grid'], + td: ['gridcell'], + }], + + // Tab key navigation should be limited to elements on the page that can be interacted with. + // https://github.com/jsx-eslint/eslint-plugin-jsx-a11y/blob/master/docs/rules/no-noninteractive-tabindex.md + 'jsx-a11y/no-noninteractive-tabindex': ['error', { + tags: [], + roles: ['tabpanel'], + allowExpressionValues: true, + }], + + // require onBlur instead of onChange + // https://github.com/jsx-eslint/eslint-plugin-jsx-a11y/blob/master/docs/rules/no-onchange.md + 'jsx-a11y/no-onchange': 'off', + + // ensure HTML elements do not specify redundant ARIA roles + // https://github.com/jsx-eslint/eslint-plugin-jsx-a11y/blob/master/docs/rules/no-redundant-roles.md + 'jsx-a11y/no-redundant-roles': ['error', { + nav: ['navigation'], + }], + + // Enforce that DOM elements without semantic behavior not have interaction handlers + // https://github.com/jsx-eslint/eslint-plugin-jsx-a11y/blob/master/docs/rules/no-static-element-interactions.md + 'jsx-a11y/no-static-element-interactions': ['error', { + handlers: [ + 'onClick', + 'onMouseDown', + 'onMouseUp', + 'onKeyPress', + 'onKeyDown', + 'onKeyUp', + ] + }], + + // Enforce that elements with ARIA roles must have all required attributes + // for that role. + // https://github.com/jsx-eslint/eslint-plugin-jsx-a11y/blob/master/docs/rules/role-has-required-aria-props.md + 'jsx-a11y/role-has-required-aria-props': 'error', + + // Enforce that elements with explicit or implicit roles defined contain + // only aria-* properties supported by that role. + // https://github.com/jsx-eslint/eslint-plugin-jsx-a11y/blob/master/docs/rules/role-supports-aria-props.md + 'jsx-a11y/role-supports-aria-props': 'error', + + // only allow to have the "scope" attr + // https://github.com/jsx-eslint/eslint-plugin-jsx-a11y/blob/master/docs/rules/scope.md + 'jsx-a11y/scope': 'error', + + // Enforce tabIndex value is not greater than zero. + // https://github.com/jsx-eslint/eslint-plugin-jsx-a11y/blob/master/docs/rules/tabindex-no-positive.md + 'jsx-a11y/tabindex-no-positive': 'error', + + // ---------------------------------------------------- + // Rules that no longer exist in eslint-plugin-jsx-a11y + // ---------------------------------------------------- + + // require that JSX labels use "htmlFor" + // https://github.com/jsx-eslint/eslint-plugin-jsx-a11y/blob/master/docs/rules/label-has-for.md + // deprecated: replaced by `label-has-associated-control` rule + 'jsx-a11y/label-has-for': ['off', { + components: [], + required: { + every: ['nesting', 'id'], + }, + allowChildren: false, + }], + + // Ensures anchor text is not ambiguous + // https://github.com/jsx-eslint/eslint-plugin-jsx-a11y/blob/93f78856655696a55309440593e0948c6fb96134/docs/rules/anchor-ambiguous-text.md + // TODO: semver-major, enable + 'jsx-a11y/anchor-ambiguous-text': 'off', + + // Enforce that aria-hidden="true" is not set on focusable elements. + // https://github.com/jsx-eslint/eslint-plugin-jsx-a11y/blob/93f78856655696a55309440593e0948c6fb96134/docs/rules/no-aria-hidden-on-focusable.md + // TODO: semver-major, enable + 'jsx-a11y/no-aria-hidden-on-focusable': 'off', + + // Enforces using semantic DOM elements over the ARIA role property. + // https://github.com/jsx-eslint/eslint-plugin-jsx-a11y/blob/93f78856655696a55309440593e0948c6fb96134/docs/rules/prefer-tag-over-role.md + // TODO: semver-major, enable + 'jsx-a11y/prefer-tag-over-role': 'off', + }, +}; diff --git a/packages/eslint-config-airbnb/rules/react-hooks.js b/packages/eslint-config-airbnb/rules/react-hooks.js new file mode 100644 index 0000000000..be17c9a571 --- /dev/null +++ b/packages/eslint-config-airbnb/rules/react-hooks.js @@ -0,0 +1,21 @@ +module.exports = { + plugins: [ + 'react-hooks', + ], + + parserOptions: { + ecmaFeatures: { + jsx: true, + }, + }, + + rules: { + // Enforce Rules of Hooks + // https://github.com/facebook/react/blob/c11015ff4f610ac2924d1fc6d569a17657a404fd/packages/eslint-plugin-react-hooks/src/RulesOfHooks.js + 'react-hooks/rules-of-hooks': 'error', + + // Verify the list of the dependencies for Hooks like useEffect and similar + // https://github.com/facebook/react/blob/1204c789776cb01fbaf3e9f032e7e2ba85a44137/packages/eslint-plugin-react-hooks/src/ExhaustiveDeps.js + 'react-hooks/exhaustive-deps': 'error', + }, +}; diff --git a/packages/eslint-config-airbnb/rules/react.js b/packages/eslint-config-airbnb/rules/react.js new file mode 100644 index 0000000000..c4d29e0b39 --- /dev/null +++ b/packages/eslint-config-airbnb/rules/react.js @@ -0,0 +1,621 @@ +const baseStyleRules = require('eslint-config-airbnb-base/rules/style').rules; + +const dangleRules = baseStyleRules['no-underscore-dangle']; + +module.exports = { + plugins: [ + 'react', + ], + + parserOptions: { + ecmaFeatures: { + jsx: true, + }, + }, + + // View link below for react rules documentation + // https://github.com/jsx-eslint/eslint-plugin-react#list-of-supported-rules + rules: { + 'no-underscore-dangle': [dangleRules[0], { + ...dangleRules[1], + allow: dangleRules[1].allow.concat(['__REDUX_DEVTOOLS_EXTENSION_COMPOSE__']), + }], + + // Specify whether double or single quotes should be used in JSX attributes + // https://eslint.org/docs/rules/jsx-quotes + 'jsx-quotes': ['error', 'prefer-double'], + + 'class-methods-use-this': ['error', { + exceptMethods: [ + 'render', + 'getInitialState', + 'getDefaultProps', + 'getChildContext', + 'componentWillMount', + 'UNSAFE_componentWillMount', + 'componentDidMount', + 'componentWillReceiveProps', + 'UNSAFE_componentWillReceiveProps', + 'shouldComponentUpdate', + 'componentWillUpdate', + 'UNSAFE_componentWillUpdate', + 'componentDidUpdate', + 'componentWillUnmount', + 'componentDidCatch', + 'getSnapshotBeforeUpdate' + ], + }], + + // This rule enforces onChange or readonly attribute for checked property of input elements. + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/checked-requires-onchange-or-readonly.md + 'react/checked-requires-onchange-or-readonly': ['off', { + ignoreMissingProperties: false, + ignoreExclusiveCheckedAttribute: false + }], + + // Prevent missing displayName in a React component definition + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/display-name.md + 'react/display-name': ['off', { ignoreTranspilerName: false }], + + // Forbid certain propTypes (any, array, object) + // https://github.com/jsx-eslint/eslint-plugin-react/blob/843d71a432baf0f01f598d7cf1eea75ad6896e4b/docs/rules/forbid-prop-types.md + 'react/forbid-prop-types': ['error', { + forbid: ['any', 'array', 'object'], + checkContextTypes: true, + checkChildContextTypes: true, + }], + + // Forbid certain props on DOM Nodes + // https://github.com/jsx-eslint/eslint-plugin-react/blob/843d71a432baf0f01f598d7cf1eea75ad6896e4b/docs/rules/forbid-dom-props.md + 'react/forbid-dom-props': ['off', { forbid: [] }], + + // Enforce boolean attributes notation in JSX + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/jsx-boolean-value.md + 'react/jsx-boolean-value': ['error', 'never', { always: [] }], + + // Validate closing bracket location in JSX + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/jsx-closing-bracket-location.md + 'react/jsx-closing-bracket-location': ['error', 'line-aligned'], + + // Validate closing tag location in JSX + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/jsx-closing-tag-location.md + 'react/jsx-closing-tag-location': 'error', + + // Enforce or disallow spaces inside of curly braces in JSX attributes + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/jsx-curly-spacing.md + 'react/jsx-curly-spacing': ['error', 'never', { allowMultiline: true }], + + // Enforce event handler naming conventions in JSX + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/jsx-handler-names.md + 'react/jsx-handler-names': ['off', { + eventHandlerPrefix: 'handle', + eventHandlerPropPrefix: 'on', + }], + + // Validate props indentation in JSX + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/jsx-indent-props.md + 'react/jsx-indent-props': ['error', 2], + + // Validate JSX has key prop when in array or iterator + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/jsx-key.md + // Turned off because it has too many false positives + 'react/jsx-key': 'off', + + // Limit maximum of props on a single line in JSX + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/jsx-max-props-per-line.md + 'react/jsx-max-props-per-line': ['error', { maximum: 1, when: 'multiline' }], + + // Prevent usage of .bind() in JSX props + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/jsx-no-bind.md + 'react/jsx-no-bind': ['error', { + ignoreRefs: true, + allowArrowFunctions: true, + allowFunctions: false, + allowBind: false, + ignoreDOMComponents: true, + }], + + // Prevent duplicate props in JSX + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/jsx-no-duplicate-props.md + 'react/jsx-no-duplicate-props': ['error', { ignoreCase: true }], + + // Prevent usage of unwrapped JSX strings + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/jsx-no-literals.md + 'react/jsx-no-literals': ['off', { noStrings: true }], + + // Disallow undeclared variables in JSX + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/jsx-no-undef.md + 'react/jsx-no-undef': 'error', + + // Enforce PascalCase for user-defined JSX components + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/jsx-pascal-case.md + 'react/jsx-pascal-case': ['error', { + allowAllCaps: true, + ignore: [], + }], + + // Enforce propTypes declarations alphabetical sorting + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/sort-prop-types.md + 'react/sort-prop-types': ['off', { + ignoreCase: true, + callbacksLast: false, + requiredFirst: false, + sortShapeProp: true, + }], + + // Deprecated in favor of react/jsx-sort-props + 'react/jsx-sort-prop-types': 'off', + + // Enforce props alphabetical sorting + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/jsx-sort-props.md + 'react/jsx-sort-props': ['off', { + ignoreCase: true, + callbacksLast: false, + shorthandFirst: false, + shorthandLast: false, + noSortAlphabetically: false, + reservedFirst: true, + }], + + // Enforce defaultProps declarations alphabetical sorting + // https://github.com/jsx-eslint/eslint-plugin-react/blob/843d71a432baf0f01f598d7cf1eea75ad6896e4b/docs/rules/jsx-sort-default-props.md + 'react/jsx-sort-default-props': ['off', { + ignoreCase: true, + }], + + // Prevent React to be incorrectly marked as unused + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/jsx-uses-react.md + 'react/jsx-uses-react': ['error'], + + // Prevent variables used in JSX to be incorrectly marked as unused + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/jsx-uses-vars.md + 'react/jsx-uses-vars': 'error', + + // Prevent usage of dangerous JSX properties + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/no-danger.md + 'react/no-danger': 'warn', + + // Prevent usage of deprecated methods + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/no-deprecated.md + 'react/no-deprecated': ['error'], + + // Prevent usage of setState in componentDidMount + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/no-did-mount-set-state.md + // this is necessary for server-rendering + 'react/no-did-mount-set-state': 'off', + + // Prevent usage of setState in componentDidUpdate + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/no-did-update-set-state.md + 'react/no-did-update-set-state': 'error', + + // Prevent usage of setState in componentWillUpdate + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/no-will-update-set-state.md + 'react/no-will-update-set-state': 'error', + + // Prevent direct mutation of this.state + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/no-direct-mutation-state.md + 'react/no-direct-mutation-state': 'off', + + // Prevent usage of isMounted + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/no-is-mounted.md + 'react/no-is-mounted': 'error', + + // Prevent multiple component definition per file + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/no-multi-comp.md + 'react/no-multi-comp': 'off', + + // Prevent usage of setState + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/no-set-state.md + 'react/no-set-state': 'off', + + // Prevent using string references + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/no-string-refs.md + 'react/no-string-refs': 'error', + + // Prevent usage of unknown DOM property + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/no-unknown-property.md + 'react/no-unknown-property': 'error', + + // Require ES6 class declarations over React.createClass + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/prefer-es6-class.md + 'react/prefer-es6-class': ['error', 'always'], + + // Require stateless functions when not using lifecycle methods, setState or ref + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/prefer-stateless-function.md + 'react/prefer-stateless-function': ['error', { ignorePureComponents: true }], + + // Prevent missing props validation in a React component definition + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/prop-types.md + 'react/prop-types': ['error', { + ignore: [], + customValidators: [], + skipUndeclared: false + }], + + // Prevent missing React when using JSX + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/react-in-jsx-scope.md + 'react/react-in-jsx-scope': 'error', + + // Require render() methods to return something + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/require-render-return.md + 'react/require-render-return': 'error', + + // Prevent extra closing tags for components without children + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/self-closing-comp.md + 'react/self-closing-comp': 'error', + + // Enforce component methods order + // https://github.com/jsx-eslint/eslint-plugin-react/blob/843d71a432baf0f01f598d7cf1eea75ad6896e4b/docs/rules/sort-comp.md + 'react/sort-comp': ['error', { + order: [ + 'static-variables', + 'static-methods', + 'instance-variables', + 'lifecycle', + '/^handle.+$/', + '/^on.+$/', + 'getters', + 'setters', + '/^(get|set)(?!(InitialState$|DefaultProps$|ChildContext$)).+$/', + 'instance-methods', + 'everything-else', + 'rendering', + ], + groups: { + lifecycle: [ + 'displayName', + 'propTypes', + 'contextTypes', + 'childContextTypes', + 'mixins', + 'statics', + 'defaultProps', + 'constructor', + 'getDefaultProps', + 'getInitialState', + 'state', + 'getChildContext', + 'getDerivedStateFromProps', + 'componentWillMount', + 'UNSAFE_componentWillMount', + 'componentDidMount', + 'componentWillReceiveProps', + 'UNSAFE_componentWillReceiveProps', + 'shouldComponentUpdate', + 'componentWillUpdate', + 'UNSAFE_componentWillUpdate', + 'getSnapshotBeforeUpdate', + 'componentDidUpdate', + 'componentDidCatch', + 'componentWillUnmount' + ], + rendering: [ + '/^render.+$/', + 'render' + ], + }, + }], + + // Prevent missing parentheses around multilines JSX + // https://github.com/jsx-eslint/eslint-plugin-react/blob/843d71a432baf0f01f598d7cf1eea75ad6896e4b/docs/rules/jsx-wrap-multilines.md + 'react/jsx-wrap-multilines': ['error', { + declaration: 'parens-new-line', + assignment: 'parens-new-line', + return: 'parens-new-line', + arrow: 'parens-new-line', + condition: 'parens-new-line', + logical: 'parens-new-line', + prop: 'parens-new-line', + }], + + // Require that the first prop in a JSX element be on a new line when the element is multiline + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/jsx-first-prop-new-line.md + 'react/jsx-first-prop-new-line': ['error', 'multiline-multiprop'], + + // Enforce spacing around jsx equals signs + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/jsx-equals-spacing.md + 'react/jsx-equals-spacing': ['error', 'never'], + + // Enforce JSX indentation + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/jsx-indent.md + 'react/jsx-indent': ['error', 2], + + // Disallow target="_blank" on links + // https://github.com/jsx-eslint/eslint-plugin-react/blob/ac102885765be5ff37847a871f239c6703e1c7cc/docs/rules/jsx-no-target-blank.md + 'react/jsx-no-target-blank': ['error', { enforceDynamicLinks: 'always' }], + + // only .jsx files may have JSX + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/jsx-filename-extension.md + 'react/jsx-filename-extension': ['error', { extensions: ['.jsx'] }], + + // prevent accidental JS comments from being injected into JSX as text + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/jsx-no-comment-textnodes.md + 'react/jsx-no-comment-textnodes': 'error', + + // disallow using React.render/ReactDOM.render's return value + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/no-render-return-value.md + 'react/no-render-return-value': 'error', + + // require a shouldComponentUpdate method, or PureRenderMixin + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/require-optimization.md + 'react/require-optimization': ['off', { allowDecorators: [] }], + + // warn against using findDOMNode() + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/no-find-dom-node.md + 'react/no-find-dom-node': 'error', + + // Forbid certain props on Components + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/forbid-component-props.md + 'react/forbid-component-props': ['off', { forbid: [] }], + + // Forbid certain elements + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/forbid-elements.md + 'react/forbid-elements': ['off', { forbid: [], }], + + // Prevent problem with children and props.dangerouslySetInnerHTML + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/no-danger-with-children.md + 'react/no-danger-with-children': 'error', + + // Prevent unused propType definitions + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/no-unused-prop-types.md + 'react/no-unused-prop-types': ['error', { + customValidators: [ + ], + skipShapeProps: true, + }], + + // Require style prop value be an object or var + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/style-prop-object.md + 'react/style-prop-object': 'error', + + // Prevent invalid characters from appearing in markup + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/no-unescaped-entities.md + 'react/no-unescaped-entities': 'error', + + // Prevent passing of children as props + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/no-children-prop.md + 'react/no-children-prop': 'error', + + // Validate whitespace in and around the JSX opening and closing brackets + // https://github.com/jsx-eslint/eslint-plugin-react/blob/843d71a432baf0f01f598d7cf1eea75ad6896e4b/docs/rules/jsx-tag-spacing.md + 'react/jsx-tag-spacing': ['error', { + closingSlash: 'never', + beforeSelfClosing: 'always', + afterOpening: 'never', + beforeClosing: 'never', + }], + + // Enforce spaces before the closing bracket of self-closing JSX elements + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/jsx-space-before-closing.md + // Deprecated in favor of jsx-tag-spacing + 'react/jsx-space-before-closing': ['off', 'always'], + + // Prevent usage of Array index in keys + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/no-array-index-key.md + 'react/no-array-index-key': 'error', + + // Enforce a defaultProps definition for every prop that is not a required prop + // https://github.com/jsx-eslint/eslint-plugin-react/blob/843d71a432baf0f01f598d7cf1eea75ad6896e4b/docs/rules/require-default-props.md + 'react/require-default-props': ['error', { + forbidDefaultForRequired: true, + }], + + // Forbids using non-exported propTypes + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/forbid-foreign-prop-types.md + // this is intentionally set to "warn". it would be "error", + // but it's only critical if you're stripping propTypes in production. + 'react/forbid-foreign-prop-types': ['warn', { allowInPropTypes: true }], + + // Prevent void DOM elements from receiving children + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/void-dom-elements-no-children.md + 'react/void-dom-elements-no-children': 'error', + + // Enforce all defaultProps have a corresponding non-required PropType + // https://github.com/jsx-eslint/eslint-plugin-react/blob/9e13ae2c51e44872b45cc15bf1ac3a72105bdd0e/docs/rules/default-props-match-prop-types.md + 'react/default-props-match-prop-types': ['error', { allowRequiredDefaults: false }], + + // Prevent usage of shouldComponentUpdate when extending React.PureComponent + // https://github.com/jsx-eslint/eslint-plugin-react/blob/9e13ae2c51e44872b45cc15bf1ac3a72105bdd0e/docs/rules/no-redundant-should-component-update.md + 'react/no-redundant-should-component-update': 'error', + + // Prevent unused state values + // https://github.com/jsx-eslint/eslint-plugin-react/pull/1103/ + 'react/no-unused-state': 'error', + + // Enforces consistent naming for boolean props + // https://github.com/jsx-eslint/eslint-plugin-react/blob/843d71a432baf0f01f598d7cf1eea75ad6896e4b/docs/rules/boolean-prop-naming.md + 'react/boolean-prop-naming': ['off', { + propTypeNames: ['bool', 'mutuallyExclusiveTrueProps'], + rule: '^(is|has)[A-Z]([A-Za-z0-9]?)+', + message: '', + }], + + // Prevents common casing typos + // https://github.com/jsx-eslint/eslint-plugin-react/blob/73abadb697034b5ccb514d79fb4689836fe61f91/docs/rules/no-typos.md + 'react/no-typos': 'error', + + // Enforce curly braces or disallow unnecessary curly braces in JSX props and/or children + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/jsx-curly-brace-presence.md + 'react/jsx-curly-brace-presence': ['error', { props: 'never', children: 'never' }], + + // One JSX Element Per Line + // https://github.com/jsx-eslint/eslint-plugin-react/blob/843d71a432baf0f01f598d7cf1eea75ad6896e4b/docs/rules/jsx-one-expression-per-line.md + 'react/jsx-one-expression-per-line': ['error', { allow: 'single-child' }], + + // Enforce consistent usage of destructuring assignment of props, state, and context + // https://github.com/jsx-eslint/eslint-plugin-react/blob/843d71a432baf0f01f598d7cf1eea75ad6896e4b/docs/rules/destructuring-assignment.md + 'react/destructuring-assignment': ['error', 'always'], + + // Prevent using this.state within a this.setState + // https://github.com/jsx-eslint/eslint-plugin-react/blob/843d71a432baf0f01f598d7cf1eea75ad6896e4b/docs/rules/no-access-state-in-setstate.md + 'react/no-access-state-in-setstate': 'error', + + // Prevent usage of button elements without an explicit type attribute + // https://github.com/jsx-eslint/eslint-plugin-react/blob/843d71a432baf0f01f598d7cf1eea75ad6896e4b/docs/rules/button-has-type.md + 'react/button-has-type': ['error', { + button: true, + submit: true, + reset: false, + }], + + // Ensures inline tags are not rendered without spaces between them + 'react/jsx-child-element-spacing': 'off', + + // Prevent this from being used in stateless functional components + // https://github.com/jsx-eslint/eslint-plugin-react/blob/843d71a432baf0f01f598d7cf1eea75ad6896e4b/docs/rules/no-this-in-sfc.md + 'react/no-this-in-sfc': 'error', + + // Validate JSX maximum depth + // https://github.com/jsx-eslint/eslint-plugin-react/blob/abe8381c0d6748047224c430ce47f02e40160ed0/docs/rules/jsx-max-depth.md + 'react/jsx-max-depth': 'off', + + // Disallow multiple spaces between inline JSX props + // https://github.com/jsx-eslint/eslint-plugin-react/blob/ac102885765be5ff37847a871f239c6703e1c7cc/docs/rules/jsx-props-no-multi-spaces.md + 'react/jsx-props-no-multi-spaces': 'error', + + // Prevent usage of UNSAFE_ methods + // https://github.com/jsx-eslint/eslint-plugin-react/blob/157cc932be2cfaa56b3f5b45df6f6d4322a2f660/docs/rules/no-unsafe.md + 'react/no-unsafe': 'off', + + // Enforce shorthand or standard form for React fragments + // https://github.com/jsx-eslint/eslint-plugin-react/blob/bc976b837abeab1dffd90ac6168b746a83fc83cc/docs/rules/jsx-fragments.md + 'react/jsx-fragments': ['error', 'syntax'], + + // Enforce linebreaks in curly braces in JSX attributes and expressions. + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/jsx-curly-newline.md + 'react/jsx-curly-newline': ['error', { + multiline: 'consistent', + singleline: 'consistent', + }], + + // Enforce state initialization style + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/state-in-constructor.md + // TODO: set to "never" once babel-preset-airbnb supports public class fields + 'react/state-in-constructor': ['error', 'always'], + + // Enforces where React component static properties should be positioned + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/static-property-placement.md + // TODO: set to "static public field" once babel-preset-airbnb supports public class fields + 'react/static-property-placement': ['error', 'property assignment'], + + // Disallow JSX props spreading + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/jsx-props-no-spreading.md + 'react/jsx-props-no-spreading': ['error', { + html: 'enforce', + custom: 'enforce', + explicitSpread: 'ignore', + exceptions: [], + }], + + // Enforce that props are read-only + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/prefer-read-only-props.md + 'react/prefer-read-only-props': 'off', + + // Prevent usage of `javascript:` URLs + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/jsx-no-script-url.md + 'react/jsx-no-script-url': ['error', [ + { + name: 'Link', + props: ['to'], + }, + ]], + + // Disallow unnecessary fragments + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/jsx-no-useless-fragment.md + 'react/jsx-no-useless-fragment': 'error', + + // Prevent adjacent inline elements not separated by whitespace + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/no-adjacent-inline-elements.md + // TODO: enable? semver-major + 'react/no-adjacent-inline-elements': 'off', + + // Enforce a specific function type for function components + // https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/function-component-definition.md + 'react/function-component-definition': ['error', { + namedComponents: ['function-declaration', 'function-expression'], + unnamedComponents: 'function-expression', + }], + + // Enforce a new line after jsx elements and expressions + // https://github.com/jsx-eslint/eslint-plugin-react/blob/e2eaadae316f9506d163812a09424eb42698470a/docs/rules/jsx-newline.md + 'react/jsx-newline': 'off', + + // Prevent react contexts from taking non-stable values + // https://github.com/jsx-eslint/eslint-plugin-react/blob/e2eaadae316f9506d163812a09424eb42698470a/docs/rules/jsx-no-constructed-context-values.md + 'react/jsx-no-constructed-context-values': 'error', + + // Prevent creating unstable components inside components + // https://github.com/jsx-eslint/eslint-plugin-react/blob/c2a790a3472eea0f6de984bdc3ee2a62197417fb/docs/rules/no-unstable-nested-components.md + 'react/no-unstable-nested-components': 'error', + + // Enforce that namespaces are not used in React elements + // https://github.com/jsx-eslint/eslint-plugin-react/blob/8785c169c25b09b33c95655bf508cf46263bc53f/docs/rules/no-namespace.md + 'react/no-namespace': 'error', + + // Prefer exact proptype definitions + // https://github.com/jsx-eslint/eslint-plugin-react/blob/8785c169c25b09b33c95655bf508cf46263bc53f/docs/rules/prefer-exact-props.md + 'react/prefer-exact-props': 'error', + + // Lifecycle methods should be methods on the prototype, not class fields + // https://github.com/jsx-eslint/eslint-plugin-react/blob/21e01b61af7a38fc86d94f27eb66cda8054582ed/docs/rules/no-arrow-function-lifecycle.md + 'react/no-arrow-function-lifecycle': 'error', + + // Prevent usage of invalid attributes + // https://github.com/jsx-eslint/eslint-plugin-react/blob/21e01b61af7a38fc86d94f27eb66cda8054582ed/docs/rules/no-invalid-html-attribute.md + 'react/no-invalid-html-attribute': 'error', + + // Prevent declaring unused methods of component class + // https://github.com/jsx-eslint/eslint-plugin-react/blob/21e01b61af7a38fc86d94f27eb66cda8054582ed/docs/rules/no-unused-class-component-methods.md + 'react/no-unused-class-component-methods': 'error', + + // Ensure destructuring and symmetric naming of useState hook value and setter variables + // https://github.com/jsx-eslint/eslint-plugin-react/blob/c8833f301314dab3e79ef7ac4cf863e4d5fa0019/docs/rules/hook-use-state.md + // TODO: semver-major, enable + 'react/hook-use-state': 'off', + + // Enforce sandbox attribute on iframe elements + // https://github.com/jsx-eslint/eslint-plugin-react/blob/c8833f301314dab3e79ef7ac4cf863e4d5fa0019/docs/rules/iframe-missing-sandbox.md + // TODO: semver-major, enable + 'react/iframe-missing-sandbox': 'off', + + // Prevent problematic leaked values from being rendered + // https://github.com/jsx-eslint/eslint-plugin-react/blob/c42b624d0fb9ad647583a775ab9751091eec066f/docs/rules/jsx-no-leaked-render.md + // TODO: semver-major, enable + 'react/jsx-no-leaked-render': 'off', + + // https://github.com/jsx-eslint/eslint-plugin-react/blob/66b58dd4864678eb869a7bf434c72ff7ac530eb1/docs/rules/no-object-type-as-default-prop.md + // TODO: semver-major, enable + 'react/no-object-type-as-default-prop': 'off', + + // https://github.com/jsx-eslint/eslint-plugin-react/blob/66b58dd4864678eb869a7bf434c72ff7ac530eb1/docs/rules/sort-default-props.md + // TODO: semver-major, enable? + 'react/sort-default-props': ['off', { + ignoreCase: false + }], + + // https://github.com/jsx-eslint/eslint-plugin-react/blob/9668ee0762acd5c23f53cd3a372e2d8d9563944d/docs/rules/forward-ref-uses-ref.md + // TODO: semver-major, enable + 'react/forward-ref-uses-ref': 'off', + + // https://github.com/jsx-eslint/eslint-plugin-react/blob/9668ee0762acd5c23f53cd3a372e2d8d9563944d/docs/rules/jsx-props-no-spread-multi.md + // TODO: semver-major, enable + 'react/jsx-props-no-spread-multi': 'off', + }, + + settings: { + 'import/resolver': { + node: { + extensions: ['.js', '.jsx', '.json'] + } + }, + react: { + pragma: 'React', + version: 'detect', + }, + propWrapperFunctions: [ + 'forbidExtraProps', // https://www.npmjs.com/package/airbnb-prop-types + 'exact', // https://www.npmjs.com/package/prop-types-exact + 'Object.freeze', // https://tc39.github.io/ecma262/#sec-object.freeze + ], + } +}; diff --git a/packages/eslint-config-airbnb/test/.eslintrc b/packages/eslint-config-airbnb/test/.eslintrc new file mode 100644 index 0000000000..9c23197fab --- /dev/null +++ b/packages/eslint-config-airbnb/test/.eslintrc @@ -0,0 +1,9 @@ +{ + "rules": { + // disabled because I find it tedious to write tests while following this rule + "no-shadow": 0, + + // tests uses `t` for tape + "id-length": [2, {"min": 2, "properties": "never", "exceptions": ["t"]}] + } +} diff --git a/packages/eslint-config-airbnb/test/requires.js b/packages/eslint-config-airbnb/test/requires.js new file mode 100644 index 0000000000..72f4ab8078 --- /dev/null +++ b/packages/eslint-config-airbnb/test/requires.js @@ -0,0 +1,15 @@ +/* eslint strict: 0, global-require: 0 */ + +'use strict'; + +const test = require('tape'); + +test('all entry points parse', (t) => { + t.doesNotThrow(() => require('..'), 'index does not throw'); + t.doesNotThrow(() => require('../base'), 'base does not throw'); + t.doesNotThrow(() => require('../legacy'), 'legacy does not throw'); + t.doesNotThrow(() => require('../whitespace'), 'whitespace does not throw'); + t.doesNotThrow(() => require('../hooks'), 'hooks does not throw'); + + t.end(); +}); diff --git a/packages/eslint-config-airbnb/test/test-base.js b/packages/eslint-config-airbnb/test/test-base.js new file mode 100644 index 0000000000..8f3f054d29 --- /dev/null +++ b/packages/eslint-config-airbnb/test/test-base.js @@ -0,0 +1,35 @@ +import fs from 'fs'; +import path from 'path'; +import test from 'tape'; + +const base = require('../base'); + +const files = { base }; + +const rulesDir = path.join(__dirname, '../rules'); +fs.readdirSync(rulesDir).forEach((name) => { + if (name === 'react.js' || name === 'react-a11y.js') { + return; + } + + // eslint-disable-next-line import/no-dynamic-require + files[name] = require(path.join(rulesDir, name)); // eslint-disable-line global-require +}); + +Object.keys(files).forEach((name) => { + const config = files[name]; + + test(`${name}: does not reference react`, (t) => { + t.plan(2); + + // scan plugins for react and fail if it is found + const hasReactPlugin = Object.prototype.hasOwnProperty.call(config, 'plugins') + && config.plugins.indexOf('react') !== -1; + t.notOk(hasReactPlugin, 'there is no react plugin'); + + // scan rules for react/ and fail if any exist + const reactRuleIds = Object.keys(config.rules) + .filter((ruleId) => ruleId.indexOf('react/') === 0); + t.deepEquals(reactRuleIds, [], 'there are no react/ rules'); + }); +}); diff --git a/packages/eslint-config-airbnb/test/test-react-order.js b/packages/eslint-config-airbnb/test/test-react-order.js new file mode 100644 index 0000000000..0ab4f937f7 --- /dev/null +++ b/packages/eslint-config-airbnb/test/test-react-order.js @@ -0,0 +1,132 @@ +import test from 'tape'; +import { CLIEngine, ESLint } from 'eslint'; +import eslintrc from '..'; +import reactRules from '../rules/react'; +import reactA11yRules from '../rules/react-a11y'; + +const rules = { + // It is okay to import devDependencies in tests. + 'import/no-extraneous-dependencies': [2, { devDependencies: true }], + // this doesn't matter for tests + 'lines-between-class-members': 0, + // otherwise we need some junk in our fixture code + 'react/no-unused-class-component-methods': 0, +}; +const cli = new (CLIEngine || ESLint)({ + useEslintrc: false, + baseConfig: eslintrc, + ...(CLIEngine ? { rules } : { overrideConfig: { rules } }), +}); + +async function lint(text) { + // @see https://eslint.org/docs/developer-guide/nodejs-api.html#executeonfiles + // @see https://eslint.org/docs/developer-guide/nodejs-api.html#executeontext + const linter = CLIEngine ? cli.executeOnText(text) : await cli.lintText(text); + return (CLIEngine ? linter.results : linter)[0]; +} + +function wrapComponent(body) { + return `\ +import React from 'react'; + +export default class MyComponent extends React.Component { +/* eslint no-empty-function: 0, class-methods-use-this: 0 */ +${body}} +`; +} + +test('validate react methods order', (t) => { + t.test('make sure our eslintrc has React and JSX linting dependencies', (t) => { + t.plan(2); + t.deepEqual(reactRules.plugins, ['react']); + t.deepEqual(reactA11yRules.plugins, ['jsx-a11y', 'react']); + }); + + t.test('passes a good component', async (t) => { + const result = await lint(wrapComponent(` + componentDidMount() {} + handleSubmit() {} + onButtonAClick() {} + setFoo() {} + getFoo() {} + setBar() {} + someMethod() {} + renderDogs() {} + render() { return
; } +`)); + + t.notOk(result.warningCount, 'no warnings'); + t.deepEquals(result.messages, [], 'no messages in results'); + t.notOk(result.errorCount, 'no errors'); + }); + + t.test('order: when random method is first', async (t) => { + const result = await lint(wrapComponent(` + someMethod() {} + componentDidMount() {} + setFoo() {} + getFoo() {} + setBar() {} + renderDogs() {} + render() { return
; } +`)); + + t.ok(result.errorCount, 'fails'); + t.deepEqual(result.messages.map((msg) => msg.ruleId), ['react/sort-comp'], 'fails due to sort'); + }); + + t.test('order: when random method after lifecycle methods', async (t) => { + const result = await lint(wrapComponent(` + componentDidMount() {} + someMethod() {} + setFoo() {} + getFoo() {} + setBar() {} + renderDogs() {} + render() { return
; } +`)); + + t.ok(result.errorCount, 'fails'); + t.deepEqual(result.messages.map((msg) => msg.ruleId), ['react/sort-comp'], 'fails due to sort'); + }); + + t.test('order: when handler method with `handle` prefix after method with `on` prefix', async (t) => { + const result = await lint(wrapComponent(` + componentDidMount() {} + onButtonAClick() {} + handleSubmit() {} + setFoo() {} + getFoo() {} + render() { return
; } +`)); + + t.ok(result.errorCount, 'fails'); + t.deepEqual(result.messages.map((msg) => msg.ruleId), ['react/sort-comp'], 'fails due to sort'); + }); + + t.test('order: when lifecycle methods after event handler methods', async (t) => { + const result = await lint(wrapComponent(` + handleSubmit() {} + componentDidMount() {} + setFoo() {} + getFoo() {} + render() { return
; } +`)); + + t.ok(result.errorCount, 'fails'); + t.deepEqual(result.messages.map((msg) => msg.ruleId), ['react/sort-comp'], 'fails due to sort'); + }); + + t.test('order: when event handler methods after getters and setters', async (t) => { + const result = await lint(wrapComponent(` + componentDidMount() {} + setFoo() {} + getFoo() {} + handleSubmit() {} + render() { return
; } +`)); + + t.ok(result.errorCount, 'fails'); + t.deepEqual(result.messages.map((msg) => msg.ruleId), ['react/sort-comp'], 'fails due to sort'); + }); +}); diff --git a/packages/eslint-config-airbnb/whitespace-async.js b/packages/eslint-config-airbnb/whitespace-async.js new file mode 100755 index 0000000000..06f4f89075 --- /dev/null +++ b/packages/eslint-config-airbnb/whitespace-async.js @@ -0,0 +1,49 @@ +#!/usr/bin/env node + +const { isArray } = Array; +const { entries } = Object; +const { ESLint } = require('eslint'); + +const baseConfig = require('.'); +const whitespaceRules = require('./whitespaceRules'); + +const severities = ['off', 'warn', 'error']; + +function getSeverity(ruleConfig) { + if (isArray(ruleConfig)) { + return getSeverity(ruleConfig[0]); + } + if (typeof ruleConfig === 'number') { + return severities[ruleConfig]; + } + return ruleConfig; +} + +async function onlyErrorOnRules(rulesToError, config) { + const errorsOnly = { ...config }; + const cli = new ESLint({ + useEslintrc: false, + baseConfig: config + }); + const baseRules = (await cli.calculateConfigForFile(require.resolve('./'))).rules; + + entries(baseRules).forEach((rule) => { + const ruleName = rule[0]; + const ruleConfig = rule[1]; + const severity = getSeverity(ruleConfig); + + if (rulesToError.indexOf(ruleName) === -1 && severity === 'error') { + if (isArray(ruleConfig)) { + errorsOnly.rules[ruleName] = ['warn'].concat(ruleConfig.slice(1)); + } else if (typeof ruleConfig === 'number') { + errorsOnly.rules[ruleName] = 1; + } else { + errorsOnly.rules[ruleName] = 'warn'; + } + } + }); + + return errorsOnly; +} + +onlyErrorOnRules(whitespaceRules, baseConfig).then((config) => console.log(JSON.stringify(config))); diff --git a/packages/eslint-config-airbnb/whitespace.js b/packages/eslint-config-airbnb/whitespace.js new file mode 100644 index 0000000000..01e5198671 --- /dev/null +++ b/packages/eslint-config-airbnb/whitespace.js @@ -0,0 +1,61 @@ +/* eslint global-require: 0 */ + +const { isArray } = Array; +const { entries } = Object; +const { CLIEngine } = require('eslint'); + +if (CLIEngine) { + /* eslint no-inner-declarations: 0 */ + const whitespaceRules = require('./whitespaceRules'); + + const baseConfig = require('.'); + + const severities = ['off', 'warn', 'error']; + + function getSeverity(ruleConfig) { + if (isArray(ruleConfig)) { + return getSeverity(ruleConfig[0]); + } + if (typeof ruleConfig === 'number') { + return severities[ruleConfig]; + } + return ruleConfig; + } + + function onlyErrorOnRules(rulesToError, config) { + const errorsOnly = { ...config }; + const cli = new CLIEngine({ baseConfig: config, useEslintrc: false }); + const baseRules = cli.getConfigForFile(require.resolve('./')).rules; + + entries(baseRules).forEach((rule) => { + const ruleName = rule[0]; + const ruleConfig = rule[1]; + const severity = getSeverity(ruleConfig); + + if (rulesToError.indexOf(ruleName) === -1 && severity === 'error') { + if (isArray(ruleConfig)) { + errorsOnly.rules[ruleName] = ['warn'].concat(ruleConfig.slice(1)); + } else if (typeof ruleConfig === 'number') { + errorsOnly.rules[ruleName] = 1; + } else { + errorsOnly.rules[ruleName] = 'warn'; + } + } + }); + + return errorsOnly; + } + + module.exports = onlyErrorOnRules(whitespaceRules, baseConfig); +} else { + const path = require('path'); + const { execSync } = require('child_process'); + + // NOTE: ESLint adds runtime statistics to the output (so it's no longer JSON) if TIMING is set + module.exports = JSON.parse(String(execSync(path.join(__dirname, 'whitespace-async.js'), { + env: { + ...process.env, + TIMING: undefined, + } + }))); +} diff --git a/packages/eslint-config-airbnb/whitespaceRules.js b/packages/eslint-config-airbnb/whitespaceRules.js new file mode 100644 index 0000000000..7c4cf691c3 --- /dev/null +++ b/packages/eslint-config-airbnb/whitespaceRules.js @@ -0,0 +1,64 @@ +module.exports = [ + 'array-bracket-newline', + 'array-bracket-spacing', + 'array-element-newline', + 'arrow-spacing', + 'block-spacing', + 'comma-spacing', + 'computed-property-spacing', + 'dot-location', + 'eol-last', + 'func-call-spacing', + 'function-paren-newline', + 'generator-star-spacing', + 'implicit-arrow-linebreak', + 'indent', + 'key-spacing', + 'keyword-spacing', + 'line-comment-position', + 'linebreak-style', + 'multiline-ternary', + 'newline-per-chained-call', + 'no-irregular-whitespace', + 'no-mixed-spaces-and-tabs', + 'no-multi-spaces', + 'no-regex-spaces', + 'no-spaced-func', + 'no-trailing-spaces', + 'no-whitespace-before-property', + 'nonblock-statement-body-position', + 'object-curly-newline', + 'object-curly-spacing', + 'object-property-newline', + 'one-var-declaration-per-line', + 'operator-linebreak', + 'padded-blocks', + 'padding-line-between-statements', + 'rest-spread-spacing', + 'semi-spacing', + 'semi-style', + 'space-before-blocks', + 'space-before-function-paren', + 'space-in-parens', + 'space-infix-ops', + 'space-unary-ops', + 'spaced-comment', + 'switch-colon-spacing', + 'template-tag-spacing', + 'import/newline-after-import', + + // eslint-plugin-react rules + 'react/jsx-child-element-spacing', + 'react/jsx-closing-bracket-location', + 'react/jsx-closing-tag-location', + 'react/jsx-curly-spacing', + 'react/jsx-equals-spacing', + 'react/jsx-first-prop-newline', + 'react/jsx-indent', + 'react/jsx-indent-props', + 'react/jsx-max-props-per-line', + 'react/jsx-one-expression-per-line', + 'react/jsx-space-before-closing', + 'react/jsx-tag-spacing', + 'react/jsx-wrap-multilines', +]; diff --git a/react/README.md b/react/README.md new file mode 100644 index 0000000000..a590a19672 --- /dev/null +++ b/react/README.md @@ -0,0 +1,757 @@ +# Airbnb React/JSX Style Guide + +*A mostly reasonable approach to React and JSX* + +This style guide is mostly based on the standards that are currently prevalent in JavaScript, although some conventions (i.e async/await or static class fields) may still be included or prohibited on a case-by-case basis. Currently, anything prior to stage 3 is not included nor recommended in this guide. + +## Table of Contents + + 1. [Basic Rules](#basic-rules) + 1. [Class vs `React.createClass` vs stateless](#class-vs-reactcreateclass-vs-stateless) + 1. [Mixins](#mixins) + 1. [Naming](#naming) + 1. [Declaration](#declaration) + 1. [Alignment](#alignment) + 1. [Quotes](#quotes) + 1. [Spacing](#spacing) + 1. [Props](#props) + 1. [Refs](#refs) + 1. [Parentheses](#parentheses) + 1. [Tags](#tags) + 1. [Methods](#methods) + 1. [Ordering](#ordering) + 1. [`isMounted`](#ismounted) + +## Basic Rules + + - Only include one React component per file. + - However, multiple [Stateless, or Pure, Components](https://facebook.github.io/react/docs/reusable-components.html#stateless-functions) are allowed per file. eslint: [`react/no-multi-comp`](https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/no-multi-comp.md#ignorestateless). + - Always use JSX syntax. + - Do not use `React.createElement` unless you’re initializing the app from a file that is not JSX. + - [`react/forbid-prop-types`](https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/forbid-prop-types.md) will allow `arrays` and `objects` only if it is explicitly noted what `array` and `object` contains, using `arrayOf`, `objectOf`, or `shape`. + +## Class vs `React.createClass` vs stateless + + - If you have internal state and/or refs, prefer `class extends React.Component` over `React.createClass`. eslint: [`react/prefer-es6-class`](https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/prefer-es6-class.md) [`react/prefer-stateless-function`](https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/prefer-stateless-function.md) + + ```jsx + // bad + const Listing = React.createClass({ + // ... + render() { + return
{this.state.hello}
; + } + }); + + // good + class Listing extends React.Component { + // ... + render() { + return
{this.state.hello}
; + } + } + ``` + + And if you don’t have state or refs, prefer normal functions (not arrow functions) over classes: + + ```jsx + // bad + class Listing extends React.Component { + render() { + return
{this.props.hello}
; + } + } + + // bad (relying on function name inference is discouraged) + const Listing = ({ hello }) => ( +
{hello}
+ ); + + // good + function Listing({ hello }) { + return
{hello}
; + } + ``` + +## Mixins + + - [Do not use mixins](https://facebook.github.io/react/blog/2016/07/13/mixins-considered-harmful.html). + + > Why? Mixins introduce implicit dependencies, cause name clashes, and cause snowballing complexity. Most use cases for mixins can be accomplished in better ways via components, higher-order components, or utility modules. + +## Naming + + - **Extensions**: Use `.jsx` extension for React components. eslint: [`react/jsx-filename-extension`](https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/jsx-filename-extension.md) + - **Filename**: Use PascalCase for filenames. E.g., `ReservationCard.jsx`. + - **Reference Naming**: Use PascalCase for React components and camelCase for their instances. eslint: [`react/jsx-pascal-case`](https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/jsx-pascal-case.md) + + ```jsx + // bad + import reservationCard from './ReservationCard'; + + // good + import ReservationCard from './ReservationCard'; + + // bad + const ReservationItem = ; + + // good + const reservationItem = ; + ``` + + - **Component Naming**: Use the filename as the component name. For example, `ReservationCard.jsx` should have a reference name of `ReservationCard`. However, for root components of a directory, use `index.jsx` as the filename and use the directory name as the component name: + + ```jsx + // bad + import Footer from './Footer/Footer'; + + // bad + import Footer from './Footer/index'; + + // good + import Footer from './Footer'; + ``` + + - **Higher-order Component Naming**: Use a composite of the higher-order component’s name and the passed-in component’s name as the `displayName` on the generated component. For example, the higher-order component `withFoo()`, when passed a component `Bar` should produce a component with a `displayName` of `withFoo(Bar)`. + + > Why? A component’s `displayName` may be used by developer tools or in error messages, and having a value that clearly expresses this relationship helps people understand what is happening. + + ```jsx + // bad + export default function withFoo(WrappedComponent) { + return function WithFoo(props) { + return ; + } + } + + // good + export default function withFoo(WrappedComponent) { + function WithFoo(props) { + return ; + } + + const wrappedComponentName = WrappedComponent.displayName + || WrappedComponent.name + || 'Component'; + + WithFoo.displayName = `withFoo(${wrappedComponentName})`; + return WithFoo; + } + ``` + + - **Props Naming**: Avoid using DOM component prop names for different purposes. + + > Why? People expect props like `style` and `className` to mean one specific thing. Varying this API for a subset of your app makes the code less readable and less maintainable, and may cause bugs. + + ```jsx + // bad + + + // bad + + + // good + + ``` + +## Declaration + + - Do not use `displayName` for naming components. Instead, name the component by reference. + + ```jsx + // bad + export default React.createClass({ + displayName: 'ReservationCard', + // stuff goes here + }); + + // good + export default class ReservationCard extends React.Component { + } + ``` + +## Alignment + + - Follow these alignment styles for JSX syntax. eslint: [`react/jsx-closing-bracket-location`](https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/jsx-closing-bracket-location.md) [`react/jsx-closing-tag-location`](https://github.com/jsx-eslint/eslint-plugin-react/blob/master/docs/rules/jsx-closing-tag-location.md) + + ```jsx + // bad + + + // good + + + // if props fit in one line then keep it on the same line + + + // children get indented normally + + + + + // bad + {showButton && +