WeakMap.prototype.set() - JavaScript | MDN
Try it
const weakmap = new WeakMap();
const object1 = {};
const object2 = {};
weakmap.set(object1, "foo");
weakmap.set(object2, "bar");
console.log(weakmap.get(object1));
// Expected output: "foo"
console.log(weakmap.get(object2));
// Expected output: "bar"
Syntax
Parameters
key-
The key of the entry to add to or modify within the
WeakMapobject. Must be either an object or a non-registered symbol. Object keys are compared by reference, not by value. value-
The value of the entry to add to or modify within the
WeakMapobject. Can be any value.
Return value
The WeakMap object.
Exceptions
TypeError-
Thrown if
keyis not an object or a non-registered symbol.
Examples
Using set()
js
const wm = new WeakMap();
const obj = {};
// Add new elements to the WeakMap
wm.set(obj, "foo").set(window, "bar"); // chainable
// Update an element in the WeakMap
wm.set(obj, "baz");
// Using a non-registered symbol as key
const sym = Symbol("foo");
wm.set(sym, "baz");
wm.set(Symbol.iterator, "qux");
Specifications
| Specification |
|---|
| ECMAScript® 2027 Language Specification # sec-weakmap.prototype.set |