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WeakSet() constructor

The WeakSet() constructor creates WeakSet objects.

Syntax

new WeakSet()
new WeakSet(iterable)

Note: WeakSet() can only be constructed with new. Attempting to call it without new throws a TypeError.

Parameters

iterable Optional: If an iterable object is passed, all of its elements will be added to the new WeakSet. null is treated as undefined.

Examples

Using the WeakSet object

const ws = new WeakSet();
const foo = {};
const bar = {};

ws.add(foo);
ws.add(bar);

ws.has(foo); // true
ws.has(bar); // true

ws.delete(foo); // removes foo from the set
ws.has(foo); // false, foo has been removed
ws.has(bar); // true, bar is retained

Note that foo !== bar. While they are similar objects, they are not the same object. And so they are both added to the set.

Specifications

Specification
ECMAScript Language Specification # sec-weakset-constructor

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