这篇翻译不完整。请帮忙从英语翻译这篇文章。
get()
返回 WeakMap
指定的元素。
语法
wm.get(key);
参数
- key
- 必须。 想要从
WeakMap
获取的元素的键。
返回值
返回与指定键相关联的值,如果 WeakMap
对象找不到这个键则返回 undefined
。
例子
使用 get
方法
var wm = new WeakMap(); wm.set(window, "foo"); wm.get(window); // Returns "foo". wm.get("baz"); // Returns undefined.
规范
Specification | Status | Comment |
---|---|---|
ECMAScript 2015 (6th Edition, ECMA-262) WeakMap.prototype.get |
Standard | Initial definition. |
ECMAScript 2017 Draft (ECMA-262) WeakMap.prototype.get |
Draft |
浏览器兼容性
Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari |
---|---|---|---|---|---|
Basic support | 36 | 6.0 (6.0) | 11 | 23 | 7.1 |
Feature | Android | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | Safari Mobile |
---|---|---|---|---|---|
Basic support | 未实现 | 6.0 (6.0) | 未实现 | 未实现 | 8 |
Firefox-specific notes
- Prior to SpiderMonkey 38 (Firefox 38 / Thunderbird 38 / SeaMonkey 2.35), this method threw a
TypeError
when the key parameter was not an object. However, the latest ES6 standard specifies to returnundefined
instead. Furthermore,WeakMap.prototype.get
accepted an optional second argument as a fallback value, which is not part of the standard. Both non-standard behaviors are removed in version 38 and higher (bug 1127827).