WeakMap.prototype.has()

The has() method returns a boolean indicating whether an element with the specified key exists in the WeakMap object or not.

Syntax

has(key)

Parameters

key: Required. The key of the element to test for presence in the WeakMap object.

Return value

Boolean: Returns true if an element with the specified key exists in the WeakMap object; otherwise false.

Examples

Using the has method

var 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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See also