Web/JavaScript/Reference/Global objects/WeakSet/has

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

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Syntax

ws.has(value);

Parameters

value

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

Return value

Boolean

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

Examples

Using the has method

var ws = new WeakSet();
var obj = {};
ws.add(window);

mySet.has(window);  // returns true
mySet.has(obj);     // returns false

Specifications

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

Browser compatibility

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

Legend

Full support  

Full support

No support  

No support

See also

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

WeakSet.prototype.has() by Mozilla Contributors is licensed under CC-BY-SA 2.5.