`valueOf()` 方法返回一个`Boolean`对象的原始值。

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## 语法

    bool.valueOf()

### 返回值

给定`Boolean`对象的原始值

## 描述

`Boolean`的 `valueOf` 方法返回一个`Boolean`对象或`Boolean`字面量的原始值作为布尔数据类型。

该方法通常在 JavaScript 内部调用，而不是在代码中显式调用。

## 示例

### 使用 `valueOf`

    x = new Boolean();
    myVar = x.valueOf()      // assigns false to myVar

## 规范

Specification | Status | Comment
--- | --- | ---
ECMAScript 1st Edition (ECMA-262) | Standard | Initial definition. Implemented in JavaScript 1.1.
ECMAScript 5.1 (ECMA-262) Boolean.prototype.valueOf | Standard |
ECMAScript 2015 (6th Edition, ECMA-262) Boolean.prototype.valueOf | Standard |
ECMAScript Latest Draft (ECMA-262) Boolean.prototype.valueOf | Draft |

## 浏览器兼容

The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.

Update compatibility data on GitHub

| Desktop | Mobile | Server
| Chrome | Edge | Firefox | Internet Explorer | Opera | Safari | Android webview | Chrome for Android | Edge Mobile | Firefox for Android | Opera for Android | Safari on iOS | Samsung Internet | Node.js
`valueOf` | Chrome Full support Yes | Edge Full support 12 | Firefox Full support 1 | IE Full support Yes | Opera Full support Yes | Safari Full support Yes | WebView Android Full support Yes | Chrome Android Full support Yes | Edge Mobile Full support Yes | Firefox Android Full support 4 | Opera Android Full support Yes | Safari iOS Full support Yes | Samsung Internet Android Full support Yes | nodejs Full support Yes

### Legend

Full support
  Full support

## 相关链接

- `Object.prototype.valueOf()`