Array.isArray

Array.isArray() 用于确定传递的值是否是一个Array。

Array.isArray([1, 2, 3]  // true
Array.isArray{foo: 123} // false
Array.isArray('foobar'   // false
Array.isArray(undefined  // false

语法

Array.isArray(obj)

参数

obj需要检测的值。

返回值

如果对象是Array，则为true; 否则为false。

描述

如果对象是Array ，则返回true，否则为false。

示例

// 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 }

instanceof 和 isArray

当检测Array实例时, Array.isArray 优于 instanceof,因为Array.isArray能检测iframes.

var iframe = document.createElement('iframe'
document.body.appendChild(iframe
xArray = window.frames[window.frames.length-1].Array;
var arr = new xArray(1,2,3 // [1,2,3]

// Correctly checking for Array
Array.isArray(arr  // true
// Considered harmful, because doesn't work through iframes
arr instanceof Array; // false

Polyfill

假如不存在 Array.isArray()，则在其他代码之前运行下面的代码将创建该方法

if (!Array.isArray) {
  Array.isArray = function(arg) {
    return Object.prototype.toString.call(arg) === '[object Array]';
  };
}

规范

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 Latest Draft (ECMA-262)The definition of 'Array.isArray' in that specification.	Living Standard

浏览器兼容性

Feature	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari
Basic Support	5	(Yes)	4	9	10.5	5

Feature	Android	Chrome for Android	Edge mobile	Firefox for Android	IE mobile	Opera Android	iOS Safari
Basic Support	(Yes)	(Yes)	(Yes)	4	(Yes)	(Yes)	(Yes)