Learn TypeScript 3 by Building Web Applications

Services

A service in Angular is usually a class (by convention, with the Service suffix) that provides some reusable behavior, just like MediaService in our MediaMan application.

Services are marked as injectable using the @Injectable decorator. Angular can automatically instantiate services and inject them when and where needed; we'll discuss that in the next section.

Here's an example service:

import { Injectable } from '@angular/core'; 
 
@Injectable( 
  providedIn: 'root' 
) 
export class BookServiceImpl implements BookService { 
  ... 
} 

Since components are user-facing, they are not supposed to worry too about much business logic and interaction with other parts of the application or other systems. Instead, components should focus on user experience ...