Q:

Why use back tick with ${ in const in typescript

I am going through the angular turorial and I see the below
https://angular.io/tutorial/toh-pt6
const url = `${this.heroesUrl}/${hero.id}`;

Can someone explain why I need to use ` before ${ ? Since this is typescript and similar to javascript can I not use 
 this.heroesUrl + "/" + hero.id 

Why do I need to use back tick and the ${ operation? 

A:

That is called Template literals and it's a javascript feature, it is not typescript specific.
True, you can indeed replace this:
const url = `${this.heroesUrl}/${hero.id}`;

With:
const url = this.heroesUrl + "/" hero.id;

But it is sometimes more comfortable to use the template literals, especially when the string is made out of a lot of parts. i.e.:
const url1 = protocol + "://" + host + ":" + port + "/" + path + "." + extension;
const url2 = `${protocol}://${host}:${port}/${path}.${extension}`;

