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• 句法
• 范例
• 规范
• 浏览器兼容性
• 另请参阅
• 相关话题

has() method returns a boolean indicating whether an object exists in a WeakSet or not.

The source for this interactive example is stored in a GitHub repository. If you'd like to contribute to the interactive examples project, please clone https://github.com/mdn/interactive-examples and send us a pull request.

句法

ws.has(value);
					

参数

value

Required. The object to test for presence in the WeakSet .

返回值

布尔

返回 true if an element with the specified value exists in the WeakSet object; otherwise false .

范例

使用 has 方法

var ws = new WeakSet();
var obj = {};
ws.add(window);
mySet.has(window);  // returns true
mySet.has(obj);     // returns false
					

规范

规范
ECMAScript (ECMA-262) The definition of 'WeakSet.prototype.has' in that specification.

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. 更新 GitHub 上的兼容性数据

	Desktop						Mobile						Server
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet	Node.js
has	Chrome 36	Edge 12	Firefox 34	IE No	Opera 23	Safari 9	WebView Android 37	Chrome Android 36	Firefox Android 34	Opera Android 24	Safari iOS 9	Samsung Internet Android 3.0	nodejs 0.12

图例

完整支持

完整支持

不支持

不支持

另请参阅

• WeakSet
• WeakSet.prototype.add()
• WeakSet.prototype.delete()

元数据

• 最后修改： 2020 年 1 月 22 日

相关话题

1. 标准内置对象
2. WeakSet
3. 方法
   1. WeakSet.prototype.add()
   2. WeakSet.prototype.clear()
   3. WeakSet.prototype.delete()
   4. WeakSet.prototype.has()
4. 继承：
5. Function
6. 特性
   1. Function.arguments
   2. Function.caller
   3. Function.displayName
   4. Function.length
   5. Function.name
7. 方法
   1. Function.prototype.apply()
   2. Function.prototype.bind()
   3. Function.prototype.call()
   4. Function.prototype.toSource()
   5. Function.prototype.toString()
8. Object
9. 特性
   1. Object.prototype.__proto__
   2. Object.prototype.constructor
10. 方法
    1. Object.prototype.__defineGetter__()
    2. Object.prototype.__defineSetter__()
    3. Object.prototype.__lookupGetter__()
    4. Object.prototype.__lookupSetter__()
    5. Object.prototype.hasOwnProperty()
    6. Object.prototype.isPrototypeOf()
    7. Object.prototype.propertyIsEnumerable()
    8. Object.prototype.toLocaleString()
    9. Object.prototype.toSource()
    10. Object.prototype.toString()
    11. Object.prototype.valueOf()
    12. Object.setPrototypeOf()