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The Array.isArray()
determines whether the passed value is an Array
.
Syntax
Array.isArray(obj)
Parameters
obj
- The object to be checked.
Return value
true
if the object is an Array
; otherwise, false
.
Description
If the object is an Array
, true
is returned, otherwise false
is.
See the article “Determining with absolute accuracy whether or not a JavaScript object is an array” for more details.
Examples
// all following calls return true Array.isArray([]); Array.isArray([1]); Array.isArray(new Array()); // Little known fact: Array.prototype itself is an array: Array.isArray(Array.prototype); // all following calls return false Array.isArray(); Array.isArray({}); Array.isArray(null); Array.isArray(undefined); Array.isArray(17); Array.isArray('Array'); Array.isArray(true); Array.isArray(false); Array.isArray({ __proto__: Array.prototype });
Polyfill
Running the following code before any other code will create Array.isArray()
if it's not natively available.
if (!Array.isArray) { Array.isArray = function(arg) { return Object.prototype.toString.call(arg) === '[object Array]'; }; }
Specifications
Specification | Status | Comment |
---|---|---|
ECMAScript 5.1 (ECMA-262) The definition of 'Array.isArray' in that specification. |
Standard | Initial definition. Implemented in JavaScript 1.8.5. |
ECMAScript 2015 (6th Edition, ECMA-262) The definition of 'Array.isArray' in that specification. |
Standard | |
ECMAScript 2017 Draft (ECMA-262) The definition of 'Array.isArray' in that specification. |
Draft |
Browser compatibility
Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari |
---|---|---|---|---|---|
Basic support | 5 | 4.0 (2.0) | 9 | 10.5 | 5 |
Feature | Android | Chrome for Android | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | Safari Mobile |
---|---|---|---|---|---|---|
Basic support | (Yes) | (Yes) | 4.0 (2.0) | (Yes) | (Yes) | (Yes) |
See also
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