WeakMap.prototype.get()

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.

The get() method of WeakMap instances returns a specified element from this WeakMap.

Try it

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

Syntax

js
get(key)

Parameters

key

The key of the element to return from the WeakMap object.

Return value

The element associated with the specified key in the WeakMap object. If the key can't be found, undefined is returned. Always returns undefined if key is not an object or a non-registered symbol.

Examples

Using the get() method

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

Specifications

Specification
ECMAScript® 2026 Language Specification
# sec-weakmap.prototype.get

Browser compatibility

See also