String.prototype.valueOf()

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

String 对象的 valueOf 方法返回一个String对象的原始值。该值等同于String.prototype.toString()

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

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相关链接