type-detect
type-detect
Improved typeof detection for node and the browser.
| Supported Browsers | |||||
|---|---|---|---|---|---|
| ✅ | ✅ | ✅ | ✅ | 9, 10, 11 | |
## What is Type-Detect?
Type Detect is a module which you can use to detect the type of a given object. It returns a string representation of the object's type, either using [`typeof`](http://www.ecma-international.org/ecma-262/6.0/index.html#sec-typeof-operator) or [`@@toStringTag`](http://www.ecma-international.org/ecma-262/6.0/index.html#sec-symbol.tostringtag). It also normalizes some object names for consistency among browsers.
## Why?
The `typeof` operator will only specify primitive values; everything else is `"object"` (including `null`, arrays, regexps, etc). Many developers use `Object.prototype.toString()` - which is a fine alternative and returns many more types (null returns `[object Null]`, Arrays as `[object Array]`, regexps as `[object RegExp]` etc).
Sadly, `Object.prototype.toString` is slow, and buggy. By slow - we mean it is slower than `typeof`. By buggy - we mean that some values (like Promises, the global object, iterators, dataviews, a bunch of HTML elements) all report different things in different browsers.
`type-detect` fixes all of the shortcomings with `Object.prototype.toString`. We have extra code to speed up checks of JS and DOM objects, as much as 20-30x faster for some values. `type-detect` also fixes any consistencies with these objects.
## Installation
### Node.js
`type-detect` is available on [npm](http://npmjs.org). To install it, type:
$ npm install type-detect
### Browsers
You can also use it within the browser; install via npm and use the `type-detect.js` file found within the download. For example:
```html
```
## Usage
The primary export of `type-detect` is function that can serve as a replacement for `typeof`. The results of this function will be more specific than that of native `typeof`.
```js
var type = require('type-detect');
```
#### array
```js
assert(type([]) === 'Array');
assert(type(new Array()) === 'Array');
```
#### regexp
```js
assert(type(/a-z/gi) === 'RegExp');
assert(type(new RegExp('a-z')) === 'RegExp');
```
#### function
```js
assert(type(function () {}) === 'function');
```
#### arguments
```js
(function () {
assert(type(arguments) === 'Arguments');
})();
```
#### date
```js
assert(type(new Date) === 'Date');
```
#### number
```js
assert(type(1) === 'number');
assert(type(1.234) === 'number');
assert(type(-1) === 'number');
assert(type(-1.234) === 'number');
assert(type(Infinity) === 'number');
assert(type(NaN) === 'number');
assert(type(new Number(1)) === 'Number'); // note - the object version has a capital N
```
#### string
```js
assert(type('hello world') === 'string');
assert(type(new String('hello')) === 'String'); // note - the object version has a capital S
```
#### null
```js
assert(type(null) === 'null');
assert(type(undefined) !== 'null');
```
#### undefined
```js
assert(type(undefined) === 'undefined');
assert(type(null) !== 'undefined');
```
#### object
```js
var Noop = function () {};
assert(type({}) === 'Object');
assert(type(Noop) !== 'Object');
assert(type(new Noop) === 'Object');
assert(type(new Object) === 'Object');
```
#### ECMA6 Types
All new ECMAScript 2015 objects are also supported, such as Promises and Symbols:
```js
assert(type(new Map() === 'Map');
assert(type(new WeakMap()) === 'WeakMap');
assert(type(new Set()) === 'Set');
assert(type(new WeakSet()) === 'WeakSet');
assert(type(Symbol()) === 'symbol');
assert(type(new Promise(callback) === 'Promise');
assert(type(new Int8Array()) === 'Int8Array');
assert(type(new Uint8Array()) === 'Uint8Array');
assert(type(new UInt8ClampedArray()) === 'Uint8ClampedArray');
assert(type(new Int16Array()) === 'Int16Array');
assert(type(new Uint16Array()) === 'Uint16Array');
assert(type(new Int32Array()) === 'Int32Array');
assert(type(new UInt32Array()) === 'Uint32Array');
assert(type(new Float32Array()) === 'Float32Array');
assert(type(new Float64Array()) === 'Float64Array');
assert(type(new ArrayBuffer()) === 'ArrayBuffer');
assert(type(new DataView(arrayBuffer)) === 'DataView');
```
Also, if you use `Symbol.toStringTag` to change an Objects return value of the `toString()` Method, `type()` will return this value, e.g:
```js
var myObject = {};
myObject[Symbol.toStringTag] = 'myCustomType';
assert(type(myObject) === 'myCustomType');
```