`set()` 方法为 `Map` 对象添加或更新一个指定了键（`key`）和值（`value`）的（新）键值对。

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## 语法

    myMap.set(key, value);

### 参数

key
  要添加至相应 `Map` 对象的元素的键。
value
  要添加至相应 `Map` 对象的元素的值。

### 返回值

`Map` 对象

## 示例

### 使用 `set` 方法

    var myMap = new Map();

    // 将一个新元素添加到 Map 对象
    myMap.set("bar", "foo");
    myMap.set(1, "foobar");

    // 在Map对象中更新某个元素的值
    myMap.set("bar", "baz");

### Using the `set` method with chaining

因为 Set() 方法返回 Map 对象本身，所以你可以像下面这样链式调用它:

    // Add new elements to the map with chaining.
    myMap.set('bar', 'foo')
         .set(1, 'foobar')
         .set(2, 'baz');

## 规范

规范 | 状态 | 备注
--- | --- | ---
ECMAScript 2015 (6th Edition, ECMA-262) Map.prototype.set | Standard | Initial definition.
ECMAScript Latest Draft (ECMA-262) Map.prototype.set | 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
`set` | Chrome Full support 38 | Edge Full support 12 | Firefox Full support 13 | IE Partial support 11 Notes Partial support 11 Notes Notes Returns 'undefined' instead of the 'Map' object. | Opera Full support 25 | Safari Full support 8 | WebView Android Full support 38 | Chrome Android Full support 38 | Edge Mobile Full support 12 | Firefox Android Full support 14 | Opera Android Full support 25 | Safari iOS Full support 8 | Samsung Internet Android Full support Yes | nodejs Full support Yes

### Legend

Full support
  Full support
Partial support
  Partial support
See implementation notes.
  See implementation notes.

## 参见

- `Map`
- `Map.prototype.get()`
- `Map.prototype.has()`