typescript-eslint · JoshuaKGoldberg · Jan 29, 2024 · Dec 27, 2023 · Dec 27, 2023 · Dec 27, 2023
diff --git a/packages/eslint-plugin/docs/rules/ban-tslint-comment.md b/packages/eslint-plugin/docs/rules/ban-tslint-comment.md
@@ -16,7 +16,7 @@ Useful when migrating from TSLint to ESLint. Once TSLint has been removed, this
 
 ### ❌ Incorrect
 
-```js
+```ts
 /* tslint:disable */
 /* tslint:enable */
 /* tslint:disable:rule1 rule2 rule3... */
@@ -28,7 +28,7 @@ someCode(); // tslint:disable-line
 
 ### ✅ Correct
 
-```js
+```ts
 // This is a comment that just happens to mention tslint
 /* This is a multiline comment that just happens to mention tslint */
 someCode(); // This is a comment that just happens to mention tslint

diff --git a/packages/eslint-plugin/docs/rules/consistent-type-assertions.md b/packages/eslint-plugin/docs/rules/consistent-type-assertions.md
@@ -54,22 +54,22 @@ Examples of code for `{ assertionStyle: 'as', objectLiteralTypeAssertions: 'neve
 #### ❌ Incorrect
 
 ```ts option='{ "assertionStyle": "as", "objectLiteralTypeAssertions": "never" }'
-const x = { ... } as T;
+const x = { foo: 1 } as T;
 
-function foo() {
-  return { ... } as T;
+function bar() {
+  return { foo: 1 } as T;
 }
 ```
 
 #### ✅ Correct
 
 ```ts option='{ "assertionStyle": "as", "objectLiteralTypeAssertions": "never" }'
-const x: T = { ... };
-const y = { ... } as any;
-const z = { ... } as unknown;
+const x: T = { foo: 1 };
+const y = { foo: 1 } as any;
+const z = { foo: 1 } as unknown;
 
-function foo(): T {
-  return { ... };
+function bar(): T {
+  return { foo: 1 };
 }
 ```
 
@@ -82,23 +82,25 @@ Examples of code for `{ assertionStyle: 'as', objectLiteralTypeAssertions: 'allo
 #### ❌ Incorrect
 
 ```ts option='{ "assertionStyle": "as", "objectLiteralTypeAssertions": "allow-as-parameter" }'
-const x = { ... } as T;
+const x = { foo: 1 } as T;
 
-function foo() {
-  return { ... } as T;
+function bar() {
+  return { foo: 1 } as T;
 }
 ```
 
 #### ✅ Correct
 
 ```tsx option='{ "assertionStyle": "as", "objectLiteralTypeAssertions": "allow-as-parameter" }'
-const x: T = { ... };
-const y = { ... } as any;
-const z = { ... } as unknown;
-foo({ ... } as T);
-new Clazz({ ... } as T);
-function foo() { throw { bar: 5 } as Foo }
-const foo = <Foo props={{ ... } as Bar}/>;
+const x: T = { foo: 1 };
+const y = { foo: 1 } as any;
+const z = { foo: 1 } as unknown;
+bar({ foo: 1 } as T);
+new Clazz({ foo: 1 } as T);
+function bar() {
+  throw { foo: 1 } as Foo;
+}
+const foo = <Foo props={{ bar: 1 } as Bar} />;
 ```
 
 <!--/tabs-->

diff --git a/packages/eslint-plugin/docs/rules/explicit-function-return-type.md b/packages/eslint-plugin/docs/rules/explicit-function-return-type.md
@@ -143,7 +143,7 @@ type FuncType = () => string;
 
 let arrowFn: FuncType = () => 'test';
 
-let funcExpr: FuncType = function() {
+let funcExpr: FuncType = function () {
   return 'test';
 };
 
@@ -163,19 +163,15 @@ let objectPropCast = <ObjectType>{
   foo: () => 1,
 };
 
-declare functionWithArg(arg: () => number);
+declare function functionWithArg(arg: () => number);
 functionWithArg(() => 1);
 
-declare functionWithObjectArg(arg: { method: () => number });
+declare function functionWithObjectArg(arg: { method: () => number });
 functionWithObjectArg({
   method() {
     return 1;
   },
 });
-
-const Comp: FC = () => {
-  return <button onClick={() => {}} />;
-};
 ```
 
 ### `allowHigherOrderFunctions`
@@ -271,7 +267,7 @@ function foo<T>(t: T): T {
 
 const bar = <T>(t: T): T => t;
 
-const allowedFunction(x: string) {
+function allowedFunction(x: string) {
   return x;
 }
 

diff --git a/packages/eslint-plugin/docs/rules/explicit-member-accessibility.md b/packages/eslint-plugin/docs/rules/explicit-member-accessibility.md
@@ -48,15 +48,15 @@ If you are working on a codebase within which you lint non-TypeScript code (i.e.
 
 This rule in its default state requires no configuration and will enforce that every class member has an accessibility modifier. If you would like to allow for some implicit public members then you have the following options:
 
-```ts
+```jsonc
 {
-  accessibility: 'explicit',
-  overrides: {
-    accessors: 'explicit',
-    constructors: 'no-public',
-    methods: 'explicit',
-    properties: 'off',
-    parameterProperties: 'explicit'
+  "accessibility: "explicit",
+  "overrides": {
+    "accessors": "explicit",
+    "constructors": "no-public",
+    "methods": "explicit",
+    "properties": "off",
+    "parameterProperties": "explicit"
   }
 }
 ```

diff --git a/packages/eslint-plugin/docs/rules/member-ordering.md b/packages/eslint-plugin/docs/rules/member-ordering.md
@@ -920,7 +920,6 @@ It ignores any member group types completely by specifying `"never"` for `member
 
 ```ts option='{ "default": { "memberTypes": "never", "order": "alphabetically" } }'
 interface Foo {
-  static c = 0;
   b(): void;
   a: boolean;
 
@@ -936,7 +935,6 @@ interface Foo {
 interface Foo {
   a: boolean;
   b(): void;
-  static c = 0;
 
   [a: string]: number; // Order doesn't matter (no sortable identifier)
   new (): Bar; // Order doesn't matter (no sortable identifier)

diff --git a/packages/eslint-plugin/docs/rules/no-empty-function.md b/packages/eslint-plugin/docs/rules/no-empty-function.md
@@ -60,9 +60,6 @@ class Foo {
 Examples of correct code for the `{ "allow": ["decoratedFunctions"] }` option:
 
 ```ts option='{ "allow": ["decoratedFunctions"] }' showPlaygroundButton
-@decorator()
-function foo() {}
-
 class Foo {
   @decorator()
   foo() {}

diff --git a/packages/eslint-plugin/docs/rules/no-for-in-array.md b/packages/eslint-plugin/docs/rules/no-for-in-array.md
@@ -21,7 +21,7 @@ You may have confused for-in with for-of, which iterates over the elements of th
 
 ### ❌ Incorrect
 
-```js
+```ts
 declare const array: string[];
 
 for (const i in array) {
@@ -35,7 +35,7 @@ for (const i in array) {
 
 ### ✅ Correct
 
-```js
+```ts
 declare const array: string[];
 
 for (const value of array) {
@@ -48,7 +48,7 @@ for (let i = 0; i < array.length; i += 1) {
 
 array.forEach((value, i) => {
   console.log(i, value);
-})
+});
 
 for (const [i, value] of array.entries()) {
   console.log(i, value);

diff --git a/packages/eslint-plugin/docs/rules/no-this-alias.md b/packages/eslint-plugin/docs/rules/no-this-alias.md
@@ -15,7 +15,7 @@ or not managing scope well.
 
 ### ❌ Incorrect
 
-```js
+```ts
 const self = this;
 
 setTimeout(function () {
@@ -25,7 +25,7 @@ setTimeout(function () {
 
 ### ✅ Correct
 
-```js
+```ts
 setTimeout(() => {
   this.doWork();
 });

diff --git a/packages/eslint-plugin/docs/rules/no-type-alias.md b/packages/eslint-plugin/docs/rules/no-type-alias.md
@@ -27,32 +27,42 @@ In TypeScript, type aliases serve three purposes:
 ```ts
 // this...
 type Person = {
-    firstName: string,
-    lastName: string,
-    age: number
+  firstName: string;
+  lastName: string;
+  age: number;
 };
 
-function addPerson(person : Person) { ... }
+function addPerson(person: Person) {
+  // ...
+}
 
 // is easier to read than this...
-function addPerson(person : { firstName: string, lastName: string, age: number}) { ... }
+function addPerson(person: {
+  firstName: string;
+  lastName: string;
+  age: number;
+}) {
+  // ...
+}
 ```
 
 - Act sort of like an interface, providing a set of methods and properties that must exist
   in the objects implementing the type.
 
 ```ts
 type Person = {
-    firstName: string,
-    lastName: string,
-    age: number,
-    walk: () => void,
-    talk: () => void
+  firstName: string;
+  lastName: string;
+  age: number;
+  walk: () => void;
+  talk: () => void;
 };
 
 // you know person will have 3 properties and 2 methods,
 // because the structure has already been defined.
-var person : Person = { ... }
+var person: Person = {
+  // ...
+};
 
 // so we can be sure that this will work
 person.walk();

diff --git a/packages/eslint-plugin/docs/rules/no-unnecessary-type-arguments.md b/packages/eslint-plugin/docs/rules/no-unnecessary-type-arguments.md
@@ -10,7 +10,9 @@ Type parameters in TypeScript may specify a default value.
 For example:
 
 ```ts
-function f<T = number>(...) {...}
+function f<T = number>(/* ... */) {
+  // ...
+}
 ```
 
 It is redundant to provide an explicit type parameter equal to that default: e.g. calling `f<number>(...)`.

diff --git a/packages/eslint-plugin/docs/rules/no-unnecessary-type-constraint.md b/packages/eslint-plugin/docs/rules/no-unnecessary-type-constraint.md
@@ -42,7 +42,7 @@ interface Foo<T> {}
 type Bar<T> = {};
 
 class Baz<T> {
-  qux<U> { }
+  qux<U>() {}
 }
 
 const Quux = <T>() => {};

diff --git a/packages/eslint-plugin/docs/rules/prefer-enum-initializers.md b/packages/eslint-plugin/docs/rules/prefer-enum-initializers.md
@@ -32,7 +32,7 @@ enum Direction {
 
 enum Color {
   Red,
-  Green = 'Green'
+  Green = 'Green',
   Blue = 'Blue',
 }
 ```

diff --git a/packages/eslint-plugin/docs/rules/prefer-for-of.md b/packages/eslint-plugin/docs/rules/prefer-for-of.md
@@ -18,7 +18,7 @@ This rule recommends a for-of loop when the loop index is only used to read from
 
 ### ❌ Incorrect
 
-```js
+```ts
 declare const array: string[];
 
 for (let i = 0; i < array.length; i++) {
@@ -28,7 +28,7 @@ for (let i = 0; i < array.length; i++) {
 
 ### ✅ Correct
 
-```js
+```ts
 declare const array: string[];
 
 for (const x of array) {

diff --git a/packages/eslint-plugin/docs/rules/space-before-blocks.md b/packages/eslint-plugin/docs/rules/space-before-blocks.md
@@ -13,9 +13,11 @@ It adds support for interfaces and enums.
 
 ### ❌ Incorrect
 
+<!-- prettier-ignore -->
 ```ts
 enum Breakpoint{
-  Large, Medium;
+  Large,
+  Medium,
 }
 
 interface State{
@@ -27,7 +29,8 @@ interface State{
 
 ```ts
 enum Breakpoint {
-  Large, Medium;
+  Large,
+  Medium,
 }
 
 interface State {

diff --git a/packages/eslint-plugin/docs/rules/typedef.md b/packages/eslint-plugin/docs/rules/typedef.md
@@ -298,13 +298,13 @@ const text = 'text';
 
 ```ts option='{ "variableDeclaration": true, "variableDeclarationIgnoreFunction": true }'
 const a = (): void => {};
-const b = function (): void => {};
+const b = function (): void {};
 const c: () => void = (): void => {};
 
 class Foo {
   a = (): void => {};
-  b = function (): void => {};
-  c = () => void = (): void => {};
+  b = function (): void {};
+  c: () => void = (): void => {};
 }
 ```
 

diff --git a/packages/eslint-plugin/tests/docs.test.ts b/packages/eslint-plugin/tests/docs.test.ts
@@ -1,3 +1,4 @@
+import { parseForESLint } from '@typescript-eslint/parser';
 import fs from 'fs';
 import { marked } from 'marked';
 import path from 'path';
@@ -180,6 +181,32 @@ describe('Validating rule docs', () => {
           }
         });
       }
+
+      test('must include only valid code samples', () => {
+        for (const token of tokens) {
+          if (token.type !== 'code') {
+            continue;
+          }
+
+          const lang = token.lang?.trim();
+          if (!lang || !/^tsx?\b/i.test(lang)) {
+            continue;
+          }
+
+          try {
+            parseForESLint(token.text, {
+              ecmaFeatures: {
+                jsx: /^tsx\b/i.test(lang),
+              },
+              ecmaVersion: 'latest',
+              sourceType: 'module',
+              range: true,
+            });
+          } catch {
+            throw new Error(`Parsing error:\n\n${token.text}`);
+          }
+        }
+      });
     });
   }
 });