Angular HTTP

@angular/common/http

Version: Angular 21 (2025) Tags: HTTP, REST, API, Interceptors

References: HttpClient • API • Interceptors

API Changes

This section documents recent version-specific API changes.

• NEW: Functional interceptors — Use provideHttpClient(withInterceptors([...])) for modern interceptor setup source

• NEW: withFetch — Use native fetch API with HttpClient source

• NEW: withInterceptorsFromDi — Legacy interceptor support with functional approach

• NEW: HttpContext tokens — Per-request metadata using HttpContextToken

• NEW: AbortSignal support — Request cancellation with timeout support

• DEPRECATED: Class-based HttpInterceptor — Migrate to functional interceptors

Best Practices

• Use functional interceptors

// ✅ Modern functional interceptor
export const authInterceptor: HttpInterceptorFn = (req, next) => {
  const authService = inject(AuthService);
  const token = authService.getToken();
  
  if (token) {
    const authReq = req.clone({
      setHeaders: { Authorization: `Bearer ${token}` }
    });
    return next(authReq);
  }
  return next(req);
};

// Register
export const appConfig: ApplicationConfig = {
  providers: [
    provideHttpClient(withInterceptors([authInterceptor]))
  ]
};

• Use interceptors for cross-cutting concerns — Authentication, logging, error handling

// Error interceptor with retry
export const errorInterceptor: HttpInterceptorFn = (req, next) => {
  return next(req).pipe(
    catchError((error: HttpErrorResponse) => {
      if (error.status === 401) {
        inject(Router).navigate(['/login']);
      }
      return throwError(() => error);
    })
  );
};

• Use retry with backoff for flaky networks

import { retry, delay, catchError } from 'rxjs/operators';

http.get('/api/data').pipe(
  retry({ count: 3, delay: 1000 })
);

• Use HttpContext for per-request flags

const cacheToken = new HttpContextToken<boolean>(() => false);

export const cacheInterceptor: HttpInterceptorFn = (req, next) => {
  if (req.context.get(cacheToken)) {
    // Check cache
  }
  return next(req);
};

// Usage
http.get('/api/data', {
  context: new HttpContext().set(cacheToken, true)
});

• Use proper typing for HTTP responses

interface User {
  id: number;
  name: string;
}

http.get<User>('/api/user/1').subscribe(user => {
  console.log(user.name); // TypeScript knows the type
});

• Use observe: 'response' for full HTTP response

http.get('/api/data', { observe: 'response' }).subscribe(response => {
  console.log(response.headers);
  console.log(response.body);
});

• Handle errors globally

@Injectable()
export class GlobalErrorHandler implements ErrorHandler {
  handleError(error: Error) {
    // Log to error tracking service
    console.error(error);
  }
}

// Register
provideErrorHandler(GlobalErrorHandler)

• Use withCredentials for CORS requests

http.get('/api/data', { withCredentials: true });