TypeScript : Colon vs Equal To ( Angular Tutorial )

Question

I am learning Angular4 and going through the tutorial examples.

https://angular.io/docs/ts/latest/tutorial/toh-pt1.html

I have the below code in the tutoria

Answer 1

I would say it is kind of interface but instead of implementing it you can use this class as a type:

export class Hero {
  id: number; // *2
  name: string;
}

let a: Hero = 'some call to create new hero';

It will ensure that the object is a type anything else will be cause in type error.

Here you can see it is been used as a type to create a new Hero of type Hero:

hero: Hero = {
  id: 1,
  name: 'Windstorm'
};