CODEWITHSUNDEEP
typescript
JJ F
JJ F

Reputation: 1549

What is the difference between these two ways of declaring a map in TypeScript?

In TypeScript I can delcare a map like this:

{[key:number]string}

As an example of a map whose keys are numbers and values string. But I can also do it like this:

Map<number, string>

Why do we have two ways to do the same and what is the difference among them?

Upvotes: 2

Views: 90

Answers (1)

Splox
Splox

Reputation: 771

A Map is a native JS object that holds pairs of keys and values. So you can do:

let myMap = new Map();
myMap.set('bla','blaa');
myMap.set('bla2','blaa2');

And that will create a map with those values.

Your other type, {[key:number]: string}, types an object that has the keys of type number and the values of type string. The main difference between a map and a plain object is a map's key can be anything (it doesn't have to be a string, number or Symbol unlike object) and it is also better optimized. See the MDN documentation for a full list of differences.

Upvotes: 1

Related Questions