valueOf()
方法返回一个String
对象的原始值(primitive value)。
语法
str.valueOf()
返回值
一个字符串代表着给定String
对象的初始值。
描述
该方法通常在 JavaScript 内部被调用,而不是在代码里显式调用。
示例
例子:使用 valueOf
x = new String("Hello world"); console.log(x.valueOf()) // Displays "Hello world"
说明
Specification | Status | Comment |
---|---|---|
ECMAScript 1st Edition (ECMA-262) | Standard | Initial definition. Implemented in JavaScript 1.1. |
ECMAScript 5.1 (ECMA-262) String.prototype.valueOf |
Standard | |
ECMAScript 2015 (6th Edition, ECMA-262) String.prototype.valueOf |
Standard | |
ECMAScript Latest Draft (ECMA-262) String.prototype.valueOf |
Draft |
浏览器兼容性
We're converting our compatibility data into a machine-readable JSON format. This compatibility table still uses the old format, because we haven't yet converted the data it contains.
Find out how you can help!
Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari |
---|---|---|---|---|---|
Basic support | (Yes) | (Yes) | (Yes) | (Yes) | (Yes) |
Feature | Android | Chrome for Android | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | Safari Mobile |
---|---|---|---|---|---|---|
Basic support | (Yes) | (Yes) | (Yes) | (Yes) | (Yes) | (Yes) |