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 (ECMAScript)
# sec-weakmap.prototype.has

Browser compatibility

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See also