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

new Map()
new Map(iterable)

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

iterable Optional: 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.

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

Specification
ECMAScript® 2026 Language Specification # sec-map-constructor

This page was last modified on ⁨Sep 13, 2025⁩ by MDN contributors.