Just a reasonable typeof
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' |
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() {} })) === '');$ npm install --save type-name
const typeName = require('type-name');
console.log(typeName(anyVar));Licensed under the MIT license.