WeakSet() constructor

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

iterable

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

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.

• A polyfill of WeakSet is available in core-js
• WeakSet