Theget() method ofWeakMap instances returns the value corresponding to the key in thisWeakMap, orundefined if there is none. Object values are returned as the same reference that was originally stored, not as a copy, so mutations to the returned object will be reflected anywhere that reference is held, including inside theWeakMap.

Try it

const weakmap = new WeakMap();const object1 = {};const object2 = {};weakmap.set(object1, 42);console.log(weakmap.get(object1));// Expected output: 42console.log(weakmap.get(object2));// Expected output: undefined

Syntax

get(key)

Parameters

key

The key of the value to return from theWeakMap object. Object keys are compared byreference, not by value.

Return value

The value associated with the specified key in theWeakMap object. If the key can't be found,undefined is returned. Always returnsundefined ifkey is not an object or anon-registered symbol.

Examples

Using get()

const wm = new WeakMap();wm.set(window, "foo");wm.get(window); // Returns "foo".wm.get("baz"); // Returns undefined.

Specifications

Browser compatibility

See also

• WeakMap
• WeakMap.prototype.delete()
• WeakMap.prototype.set()
• WeakMap.prototype.has()