TypeScript - how to use Map

In this article, we would like to show you how to use Maps in TypeScript.

1. Introduction

Map is a data structure that allows us to store key-value pairs.

2. Create Map

let map = new Map<string, number>();

3. Map - set, get, size method example

// create map
const map = new Map<string, number>();

// set entities
map.set('Ann', 25);
map.set('Seth', 32);
map.set('Kate', 27);

// get entities
const value1 = map.get('Ann');
console.log('Ann age: ' + value1); // Ann age: 25

const value2 = map.get('Seth');
console.log('Seth age: ' + value2); // Seth age: 32

const value3 = map.get('Kate');
console.log('Kate age: ' + value3); // Kate age: 27

// siz of map
const size = map.size;
console.log('map size: ' + size); // map size: 3

Output:

Ann age: 25
Seth age: 32
Kate age: 27
map size: 3

Note: Run this example online here.

3. Most important methods of Map:

map.set() - add key-value pair to Map
map.get() - retrieve value by key from Map
map.delete() - delete key-value pair by given key from Map
map.has() - check if there is a value for given key - return true / false
map.size() - size of the map, number of key-value pairs in Map

Note about map.set() method.
In other languages or self implemented data structures to add key-value pair to Map the method is named: put, add or set.

Reference:

1. Mozilla docs - Map