TypeScript - how to use Map

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

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

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

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// 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:

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Ann age: 25

Seth age: 32

Kate age: 27

map size: 3

Note: Run this example online here.

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.

1. Mozilla docs - Map