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 (ECMA-262)
The definition of 'WeakMap.prototype.has' in that specification.

Browser compatibility

BCD tables only load in the browser

See also