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WeakSet.prototype.has()

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

Try it

Syntax

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

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

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

Specifications

Specification
ECMAScript Language Specification
# sec-weakset.prototype.has

Browser compatibility

Desktop Mobile Server
Chrome Edge Firefox Internet Explorer Opera Safari WebView Android Chrome Android Firefox for Android Opera Android Safari on IOS Samsung Internet Deno Node.js
has
36
12
34
No
23
9
37
36
34
24
9
3.0
1.0
0.12.0

See also

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Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/WeakSet/has