JS: Map Constructor

By Xah Lee. Date: .

New in ES2015.

new Map() → creates a empty map.

new Map(iterable) → create a map from values in iterable object iterable.

const m = new Map();

// add new item
m.set(1, "n1");
m.set(2, "n2");

console.log(m) // Map { 1 => 'n1', 2 => 'n2' }

Example of array to map:

// using nested array as literal expression for map
const m = new Map([ [3, "n3"], [4, "n4"]]);
console.log(m) // Map { 3 => 'n3', 4 => 'n4' }

Any iterable object can be used as argument. [see JS: Iterable]

Convert Object To/From Map

JS: Convert Object to/from Map

Reference

ECMAScript 2015 §Keyed Collection#sec-map-constructor

Map Topic

  1. JS: the Map Object Tutorial
  2. JS: Map Object
  3. JS: Map.prototype
  4. JS: Iterate Over Map Object
  5. JS: Convert Object to/from Map
  6. JS: Map Filter
Liket it? Put $5 at patreon.

Or, Buy JavaScript in Depth

If you have a question, put $5 at patreon and message me.