WeakMap.prototype.has()
The has() method of WeakMap instances returns a boolean indicating whether an
element with the specified key exists in this WeakMap or not.
Try it
Syntax
js
has(key)
Parameters
key-
The key of the element to test for presence in the
WeakMapobject.
Return value
Returns true if an element 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 the has method
js
const wm = new WeakMap();
wm.set(window, "foo");
wm.has(window); // returns true
wm.has("baz"); // returns false
Specifications
| Specification |
|---|
| ECMAScript Language Specification # sec-weakmap.prototype.has |
Browser compatibility
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has | |||||||||||||