type-name

Just a reasonable typeof

DESCRIPTION

typeName function returns reasonable type name for input value.

description	input	result
null literal	`null`	`'null'`
undefined value	`undefined`	`'undefined'`
string literal	`'foo'`	`'string'`
number literal	`5`	`'number'`
boolean literal	`false`	`'boolean'`
regexp literal (Android 4.1+)	`/^not/`	`'RegExp'`
array literal	`['foo', 4]`	`'Array'`
object literal	`{name: 'bar'}`	`'Object'` (be careful!)
function expression	`function () {}`	`'function'`
String object	`new String('foo')`	`'String'`
Number object	`new Number('3')`	`'Number'`
Boolean object	`new Boolean('1')`	`'Boolean'`
Date object	`new Date()`	`'Date'`
RegExp object (Android 4.1+)	`new RegExp('^not', 'g')`	`'RegExp'`
Array object	`new Array()`	`'Array'`
Object object	`new Object()`	`'Object'`
Function object	`new Function('x', 'y', 'return x + y')`	`'function'` (be careful!)
Error object	`new Error('error!')`	`'Error'`
TypeError object	`new TypeError('type error!')`	`'TypeError'`
NaN	`NaN`	`'number'`
Infinity	`Infinity`	`'number'`
Math	`Math`	`'Math'`
JSON (IE8+)	`JSON`	`'JSON'`
arguments object (IE9+)	`(function(){ return arguments; })()`	`'Arguments'`
User-defined constructor	`new Person('alice', 5)`	`'Person'`
Anonymous constructor	`new AnonPerson('bob', 4)`	`''`
Named class	`new(class Foo { constructor() {} })`	`'Foo'`
Anonymous class	`new(class { constructor() {} })`	`''`
Symbol	`Symbol("FOO")`	`'symbol'`
Promise	`Promise.resolve(1)`	`'Promise'`

EXAMPLE

const typeName = require('type-name');
const assert = require('assert');

assert(typeName(null) === 'null');
assert(typeName(undefined) === 'undefined');
assert(typeName('foo') === 'string');
assert(typeName(5) === 'number');
assert(typeName(false) === 'boolean');
assert(typeName(/^not/) === 'RegExp');
assert(typeName(['foo', 4]) === 'Array');
assert(typeName({name: 'bar'}) === 'Object');
assert(typeName(function () {}) === 'function');
assert(typeName(new String('foo')) === 'String');
assert(typeName(new Number('3')) === 'Number');
assert(typeName(new Boolean('1')) === 'Boolean');
assert(typeName(new Date()) === 'Date');
assert(typeName(new RegExp('^not', 'g')) === 'RegExp');
assert(typeName(new Array()) === 'Array');
assert(typeName(new Object()) === 'Object');
assert(typeName(new Function('x', 'y', 'return x + y')) === 'function');
assert(typeName(new Error('error!')) === 'Error');
assert(typeName(new TypeError('type error!')) === 'TypeError');
assert(typeName(NaN) === 'number');
assert(typeName(Infinity) === 'number');
assert(typeName(Math) === 'Math');
assert(typeName(JSON) === 'JSON'); // IE8+
assert(typeName((function(){ return arguments; })()) === 'Arguments');  // IE9+
assert(typeName(Symbol("FOO")) === 'symbol');
assert(typeName(Promise.resolve(1)) === 'Promise');

function Person(name, age) {
    this.name = name;
    this.age = age;
}

const AnonPerson = function(name, age) {
    this.name = name;
    this.age = age;
};

assert(typeName(new Person('alice', 5)) === 'Person');
assert(typeName(new AnonPerson('bob', 4)) === '');

assert(typeName(new(class Foo { constructor() {} })) === 'Foo');
assert(typeName(new(class { constructor() {} })) === '');

INSTALL

$ npm install --save type-name

USAGE

const typeName = require('type-name');
console.log(typeName(anyVar));

AUTHOR

Takuto Wada

CONTRIBUTORS

LICENSE

Licensed under the MIT license.

License

twada/type-name

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