Array.isArray Redirect 1

The Array.isArray() method returns true if an object is an array, false if it is not.

Syntax

Array.isArray(obj)

Parameters

obj
The object to be checked.

Description

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  

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

Document Tags and Contributors

Last updated by: Sheppy,