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Map.prototype

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