WeakMap.prototype

The WeakMap.prototype property represents the prototype for the WeakMap constructor.

Description

WeakMap instances inherit from WeakMap.prototype. You can use the constructor's prototype object to add properties or methods to all WeakMap instances.

WeakMap.prototype is itself just an ordinary object:

Object.prototype.toString.call(WeakMap.prototype); // "[object Object]"

Properties

WeakMap.prototype.constructor

Returns the function that created an instance's prototype. This is the WeakMap function by default.

Methods

WeakMap.prototype.delete(key)

Removes any value associated to the key. WeakMap.prototype.has(key) will return false afterwards.

WeakMap.prototype.get(key)

Returns the value associated to the key, or undefined if there is none.

WeakMap.prototype.has(key)

Returns a Boolean asserting whether a value has been associated to the key in the WeakMap object or not.

WeakMap.prototype.set(key, value)

Sets the value for the key in the WeakMap object. Returns the WeakMap object.

WeakMap.prototype.clear()

Removes all key/value pairs from the WeakMap object. Note that it is possible to implement a WeakMap-like object that has a .clear() method by encapsulating a WeakMap object that hasn't it (see example on page WeakMap)

Specifications

Specification	Status	Comment
ECMAScript 2015 (6th Edition, ECMA-262) The definition of 'WeakMap.prototype' in that specification.	Standard	Initial definition.
ECMAScript 2017 Draft (ECMA-262) The definition of 'WeakMap.prototype' in that specification.	Draft

Browser compatibility

See also

• Map.prototype