number.valueOf

valueOf()方法返回一个被 Number对象包装的原始值。

语法

numObj.valueOf()

返回值

表示指定 Number 对象的原始值的数字

描述

该方法通常是由 JavaScript 引擎在内部隐式调用的，而不是由用户在代码中显式调用的。

示例

使用valueOf

var numObj = new Number(10
console.log(typeof numObj // object

var num = numObj.valueOf(
console.log(num           // 10
console.log(typeof num    // number

规范

Specification	Status	Comment
ECMAScript 1st Edition (ECMA-262)	Standard	Initial definition. Implemented in JavaScript 1.1.
ECMAScript 5.1 (ECMA-262)The definition of 'Number.prototype.valueOf' in that specification.	Standard
ECMAScript 2015 (6th Edition, ECMA-262)The definition of 'Number.prototype.valueOf' in that specification.	Standard
ECMAScript Latest Draft (ECMA-262)The definition of 'Number.prototype.valueOf' in that specification.	Draft

浏览器兼容性

Feature	Chrome	Firefox	Edge	Internet Explorer	Opera	Safari
Basic Support	(Yes)	(Yes)	(Yes)	(Yes)	(Yes)	(Yes)

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