WeakMap.prototype.has() - JavaScript | MDN
Try it
const weakmap = new WeakMap();
const object1 = {};
const object2 = {};
weakmap.set(object1, "foo");
console.log(weakmap.has(object1));
// Expected output: true
console.log(weakmap.has(object2));
// Expected output: false
Syntax
Parameters
Return value
Returns true if an entry with the specified key exists in the WeakMap object; otherwise false. Always returns false if key is not an object or a non-registered symbol.
Examples
Using has()
js
const wm = new WeakMap();
wm.set(window, "foo");
wm.has(window); // returns true
wm.has("baz"); // returns false
Specifications
| Specification |
|---|
| ECMAScript® 2027 Language Specification # sec-weakmap.prototype.has |