Map() constructor

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.

The Map() constructor creates Map objects.

Syntax

js
new Map()
new Map(iterable)

Note: Map() can only be constructed with new. Attempting to call it without new throws a TypeError.

If an iterable object (such as an array) is passed, all of its elements will be added to the new Map. Each element must be an object with two properties: 0 and 1, which correspond to the key and value (for example, [[1, "one"],[2, "two"]]). If you don't specify this parameter, or its value is null or undefined, the new Map is empty.

Examples

Creating a new Map

js
const myMap = new Map([
  [1, "one"],
  [2, "two"],
  [3, "three"],
]);

Specifications

Specification

ECMAScript® 2027 Language Specification
# sec-map-constructor

Browser compatibility

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Standard built-in objects
Map
Constructor
1. Map()
Static methods
1. groupBy()
Static properties
1. [Symbol.species]
Instance methods
Instance properties
1. size
Inheritance
Object/Function
Static methods
Static properties
Instance methods
Instance properties
1. __proto__
2. constructor