知名的 `Symbol.species` 是个函数值属性，其被构造函数用以创建派生对象。

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`Symbol.species` 属性的属性特性：
writable | false
enumerable | false
configurable | false

## 描述

species 访问器属性允许子类覆盖对象的默认构造函数。

## 示例

你可能想在扩展数组类 `MyArray` 上返回 `Array` 对象。 例如，当使用例如 `map()` 这样的方法返回默认的构造函数时，你希望这些方法能够返回父级的 Array 对象，以取代 `MyArray` 对象。`Symbol.species` 允许你这么做：

    class MyArray extends Array {
      // 覆盖 species 到父级的 Array 构造函数上
      static get [Symbol.species]() { return Array; }
    }
    var a = new MyArray(1,2,3);
    var mapped = a.map(x => x * x);

    console.log(mapped instanceof MyArray); // false
    console.log(mapped instanceof Array);   // true

## 规范

Specification | Status | Comment
--- | --- | ---
ECMAScript 2015 (6th Edition, ECMA-262) Symbol.species | Standard | Initial definition.
ECMAScript Latest Draft (ECMA-262) Symbol.species | Draft |

## 浏览器兼容性

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
`species` | Chrome Full support 51 | Edge Full support 13 | Firefox Full support 41 | IE No support No | Opera Full support 38 | Safari Full support 10 | WebView Android Full support 51 | Chrome Android Full support 51 | Edge Mobile Full support 14 | Firefox Android Full support 41 | Opera Android Full support 38 | Safari iOS Full support 10 | Samsung Internet Android Full support Yes | nodejs Full support 6.5.0 Full support 6.5.0 Full support 6.0.0 Disabled Disabled From version 6.0.0: this feature is behind the `--harmony` runtime flag.

### Legend

Full support
  Full support
No support
  No support
User must explicitly enable this feature.
  User must explicitly enable this feature.

## 相关链接

- `Map[@@species]`
- `Set[@@species]`