Make AJAX request before bootstrapping Angular2 application [duplicate]

Answer 1

class AuthService {
  isLoggedIn:BehaviorSubject<boolean> = BehaviorSubject<boolean>(false);
  checkLogin(http:Http) {
    return http.get(...)
    .map(result => result.json())
    .do(result => this.isLoggedIn.next(result)
  }
}

bootstrap(AppComponent, [
  HTTP_PROVIDERS,
  AuthService,
  { provide: APP_INITIALIZER, 
    useFactory: (authService:AuthService) => authService.checkLogin(),
    deps: [AuthService],
    multi: true
  }
]);

See also How to pass parameters rendered from backend to angular2 bootstrap method