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WeakSet() constructor

The WeakSet constructor lets you create WeakSet objects that store weakly held objects in a collection.

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

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
`WeakSet`	36	12	34	No	23	9	37	36	34	24	9	3.0	1.0	0.12.0
`iterable_allowed`	38	12	34	No	25	9	38	38	34	25	9	3.0	1.0	0.12.0
`null_allowed`	36	12	37	No	23	9	37	36	37	24	9	3.0	1.0	0.12.0