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

Property attributes of Map.prototype
Writable no
Enumerable no
Configurable no

Description

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

Properties

Map.prototype.constructor
Returns the function that created an instance's prototype. This is the Map function by default.
Map.prototype.size
Returns the number of key/value pairs in the Map object.

Methods

Map.prototype.clear()
Removes all key/value pairs from the Map object.
Map.prototype.delete(key)
Removes any value associated to the key and returns the value that Map.prototype.has(key) would have previously returned. Map.prototype.has(key) will return false afterwards.
Map.prototype.entries()
Returns a new Iterator object that contains an array of [key, value] for each element in the Map object in insertion order.
Map.prototype.forEach(callbackFn[, thisArg])
Calls callbackFn once for each key-value pair present in the Map object, in insertion order. If a thisArg parameter is provided to forEach, it will be used as the this value for each callback.
Map.prototype.get(key)
Returns the value associated to the key, or undefined if there is none.
Map.prototype.has(key)
Returns a boolean asserting whether a value has been associated to the key in the Map object or not.
Map.prototype.keys()
Returns a new Iterator object that contains the keys for each element in the Map object in insertion order.
Map.prototype.set(key, value)
Sets the value for the key in the Map object. Returns the Map object.
Map.prototype.values()
Returns a new Iterator object that contains the values for each element in the Map object in insertion order.
Map.prototype[@@iterator]()
Returns a new Iterator object that contains an array of [key, value] for each element in the Map object in insertion order.

Specifications

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

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
Basic support 38 13 (13) 11 25 7.1
Feature Android Chrome for Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
Basic support No support 38 13.0 (13) No support No support

8

See also

Document Tags and Contributors

 Last updated by: jozanza,