Javascript-WeakSet

WeakSet objects are collections of objects. In the WeakSet object, each object in a WeakSet may occur only once. Only all objects in a WeakSet’s collection are unique.

Syntax:

new WeakSet([iterable])

• WeakSets are collections of objects only. It doesn’t contain arbitrary values.

Instance methods:

• WeakSet.prototype.add(value) – Appends a value to the WeakSet object.
• WeakSet.prototype.delete(value) – Remove the specified object from the javascript WeakSet object.
• WeakSet.prototype.has(value) – WeakSet object contains the specified object element.

• A WeakSet object contains unique objects only.
• No reference to a stored object and they are targeted to garbage collection.

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