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WeakSet.prototype.has() - JavaScript | MDN
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  5. WeakSet
  6. WeakSet.prototype.has()
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WeakSet.prototype.has()

Baseline Widely available

This feature is well established and works across many devices and browser versions. Its been available across browsers since 2015 ..

has() , WeakSet , true false.

In this article

ws.has(value);

value

. .

Boolean

WeakSet true, false.

has

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

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

Specification
ECMAScript 2027 LanguageSpecification
# sec-weakset.prototype.has

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  2. WeakSet
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