Question

What is a WeakMap?

Answer 1

The WeakMap object is a collection of key/value pairs in which the keys are weakly referenced. In this case, keys must be objects and the values can be arbitrary values. The syntax is looking like as below,

new WeakMap([iterable]);

Let's see the below example to explain it's behavior,

var ws = new WeakMap();
var user = {};
ws.set(user);
ws.has(user); // true
ws.delete(user); // removes user from the map
ws.has(user); // false, user has been removed