Service Lifecycle.md

angular/angular#11228 (comment)

@Component({
  ...
  providers: [MyService],
  template: '<router-outlet></router-outlet>'
})
export class MyNavWrapperComponent {
  // Must inject to instantiate service for all child routes.
  // When this component is destroyed, the service will be too.
  constructor(service: MyService) { }
}

routes: Routes = [
  {
    path: '',
    component: MyNavWrapperComponent,
    children: [ ... ],
  }
]