array.unshift
unshift()方法将一个或多个元素添加到数组的开头，并返回新数组的长度。
var a = [1, 2, 3];
a.unshift(4, 5);
console.log(a); // [4, 5, 1, 2, 3]语法
arr.unshift([element1[, ...[, elementN]]])参数
element_N_要添加到数组开头的元素。
返回值
当一个对象调用该方法时，返回其length属性值。
描述
unshift方法会在调用它的类数组（array-like）对象的开始位置插入给定的参数。
示例
var arr = [1, 2];
arr.unshift(0); // result of call is 3, the new array length
// arr is [0, 1, 2]
arr.unshift(-2, -1); // = 5
// arr is [-2, -1, 0, 1, 2]
arr.unshift([-3]);
// arr is [[-3], -2, -1, 0, 1, 2]规范
Specification | Status | Comment |
|---|---|---|
ECMAScript 3rd Edition (ECMA-262) | Standard | Initial definition. Implemented in JavaScript 1.2. |
ECMAScript 5.1 (ECMA-262)The definition of 'Array.prototype.unshift' in that specification. | Standard | |
ECMAScript 2015 (6th Edition, ECMA-262)The definition of 'Array.prototype.unshift' in that specification. | Standard | |
ECMAScript Latest Draft (ECMA-262)The definition of 'Array.prototype.unshift' in that specification. | Living Standard | |
浏览器兼容性
Feature | Chrome | Edge | Firefox | Internet Explorer | Opera | Safari |
|---|---|---|---|---|---|---|
Basic Support | 1 | (Yes) | 1 | 5.5 | (Yes) | (Yes) |
Feature | Android | Chrome for Android | Edge mobile | Firefox for Android | IE mobile | Opera Android | iOS Safari |
|---|---|---|---|---|---|---|---|
Basic Support | (Yes) | (Yes) | (Yes) | 1 | (Yes) | (Yes) | (Yes) |
本文档系腾讯云开发者社区成员共同维护，如有问题请联系 cloudcommunity@tencent.com
