WeakMap.prototype.get()

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.

WeakMap 实例的 get() 方法返回该 WeakMap 中的指定元素。

尝试一下

const weakmap1 = new WeakMap();
const object1 = {};
const object2 = {};

weakmap1.set(object1, 42);

console.log(weakmap1.get(object1));
// Expected output: 42

console.log(weakmap1.get(object2));
// Expected output: undefined

语法

js
get(key)

参数

key

要从 WeakMap 对象返回的元素的键。

返回值

WeakMap 对象中与指定键相关联的元素。如果找不到该键,则返回 undefined。如果 key 不是对象或非全局注册的符号,则始终返回 undefined

示例

使用 get() 方法

js
const wm = new WeakMap();
wm.set(window, "foo");

wm.get(window); // 返回 "foo"。
wm.get("baz"); // 返回 undefined。

规范

Specification
ECMAScript® 2025 Language Specification
# sec-weakmap.prototype.get

浏览器兼容性

Report problems with this compatibility data on GitHub
desktopmobileserver
Chrome
Edge
Firefox
Opera
Safari
Chrome Android
Firefox for Android
Opera Android
Safari on iOS
Samsung Internet
WebView Android
WebView on iOS
Deno
Node.js
get

Legend

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Full support
Full support
See implementation notes.

参见