已废弃
This feature is obsolete. Although it may still work in some browsers, its use is discouraged since it could be removed at any time. Try to avoid using it.

`clear()` 方法用于删除 `WeakSet` 对象的所有元素，但是已经不是 ECMAScript 的一部分了。

## 语法

    ws.clear();

## 示例

### 使用 `clear方法`

    var ws = new WeakSet();

    ws.add(window);
    ws.has(window);  // true

    ws.clear();

    ws.has(window); // false

## 规范

没有规范或草案。该方法原本计划包括在 ECMAScript 6，但是在草案 revision 28 (October 14, 2014) 被抛弃了。浏览器原先的实现不久后也被移除了，它从来不是标准的一分子。

## 浏览器支持

We're converting our compatibility data into a machine-readable JSON format. This compatibility table still uses the old format, because we haven't yet converted the data it contains. Find out how you can help!

- Desktop
- Mobile

Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari
--- | --- | --- | --- | --- | ---
Basic support | 36 | 未实现 [1] | 未实现 | 23 | 未实现

Feature | Android | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | Safari Mobile
--- | --- | --- | --- | --- | ---
Basic support | 未实现 | 未实现 [1] | 未实现 | 未实现 | 未实现

[1] Added to Firefox in version 34, but removed in version 46. See bug 1101817.

## 相关

- `WeakSet`
- `WeakSet.prototype.delete()`