Template resolver (angularjs to angular) example

template-resolver.ts

@Injectable()
export class TemplateResolver implements Resolve<string> {
  constructor(
    private templateService: TemplateService,
    @Inject('$templateCache') private $templateCache: any
  ) {}
  resolve(route: ActivatedRouteSnapshot, state: RouterStateSnapshot) {
    const templateUrl = route.data.templateUrl;
    return this.templateService
      .getTemplate(templateUrl)
      .pipe(tap(template => this.$templateCache.put(templateUrl, template)));
  }
}