该全局 `isFinite()` 函数用来判断被传入的参数值是否为一个有限数值（finite number）。在必要情况下，参数会首先转为一个数值。

## 语法

    isFinite(testValue)

### 参数

`testValue`
  用于检测有限性（finiteness）的值。

### 描述

  isFinite 是全局的方法，不与任何对象有关系。

你可以用这个方法来判定一个数字是否是有限数字。`isFinite` 方法检测它参数的数值。如果参数是 `NaN`，正无穷大或者负无穷大，会返回`false`，其他返回 `true`。

## 示例

    isFinite(Infinity);  // false
    isFinite(NaN);       // false
    isFinite(-Infinity); // false

    isFinite(0);         // true
    isFinite(2e64);      // true, 在更强壮的Number.isFinite(null)中将会得到false

    isFinite("0");       // true, 在更强壮的Number.isFinite('0')中将会得到false

## 规范

Specification | Status | Comment
--- | --- | ---
ECMAScript 3rd Edition (ECMA-262) | Standard | Initial definition.
ECMAScript 5.1 (ECMA-262) isFinite | Standard |
ECMAScript 2015 (6th Edition, ECMA-262) isFinite | Standard |
ECMAScript Latest Draft (ECMA-262) isFinite | Draft |

## 浏览器兼容性

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
`isFinite` | Chrome Full support Yes | Edge Full support Yes | 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

- `Number.isFinite()`
- `Number.NaN()`
- `Number.POSITIVE_INFINITY`
- `Number.NEGATIVE_INFINITY`