angular-http

Use httpResource() from @angular/common/http to create a reactive HTTP request tied to signals. It exposes value(), isLoading(), error(), and status() signals, and automatically refetches when the signals used in its request function change.

httpResource wraps HttpClient with signal-based state management for declarative data fetching, while HttpClient returns Observables suited for complex operator chains or one-off mutations. Use httpResource for read-heavy reactive views and HttpClient for POST, PUT, and DELETE operations.

Create a functional interceptor implementing HttpInterceptorFn that clones the request with an Authorization header, then register it via provideHttpClient with withInterceptors in app.config.ts. The interceptor runs for every outgoing request automatically.

Yes. The resource() API provides an abortSignal in its loader that automatically cancels the previous fetch when params change. With HttpClient, unsubscribe from the previous subscription or use switchMap to cancel in-flight requests.

Configure TestBed with provideHttpClientTesting, inject HttpTestingController, and use expectOne with the request URL to flush mock responses. Then assert on the resource's value() signal and call httpMock.verify() in afterEach.

Use resource() for non-HTTP async operations or custom fetch logic, such as direct fetch calls, computed async data, or third-party SDK calls. Use httpResource() when you want HttpClient-backed requests with interceptors and typed HTTP semantics.