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

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

Syntax

new WeakSet([iterable]);

Parameters

iterable: 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

var ws = new WeakSet();
var foo = {};
var 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 (ECMA-262)The definition of 'WeakSet constructor' in that specification.

Browser compatibility

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
`WeakSet()` constructor	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
`new WeakSet(iterable)`	Chrome Full support 38	Edge Full support 12	Firefox Full support 34	IE No support No	Opera Full support 25	Safari Full support 9	WebView Android Full support 38	Chrome Android Full support 38	Firefox Android Full support 34	Opera Android Full support 25	Safari iOS Full support 9	Samsung Internet Android Full support 3.0	nodejs Full support 0.12
`new WeakSet(null)`	Chrome Full support 36	Edge Full support 12	Firefox Full support 37	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 37	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