WeakMap.prototype.has()
The has()
method returns a boolean indicating whether an
element with the specified key exists in the WeakMap
object or not.
Try it
Syntax
js
has(key)
Parameters
key
-
The key of the element to test for presence in the
WeakMap
object.
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
BCD tables only load in the browser