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

JS Map Topic

  1. the Map Object Tutorial
  2. Map Object
  3. Map.prototype
  4. Iterate Over Map Object
  5. Convert Object to/from Map
  6. Map Filter
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