angular-http

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

httpResource wraps HttpClient with signal-based state management, giving you loading, error, and reload handling declaratively. HttpClient returns Observables and suits complex operator chains or one-off mutations like POST and DELETE calls.

Create a functional interceptor implementing HttpInterceptorFn that clones the request with an Authorization header, then register it via provideHttpClient(withInterceptors([authInterceptor])) in your application config.

The resource() API passes an abortSignal to its loader, which automatically cancels the previous fetch when params change. With HttpClient, unsubscribe from the prior subscription or use switchMap with debounceTime for debounced search.

Provide provideHttpClientTesting() in TestBed, inject HttpTestingController, and use expectOne() to match the request URL, then flush mock data. Assert on the resource's value() signal after flushing the response.

Use resource() for non-HTTP async operations or custom fetch logic where you control the loader function, such as direct fetch calls or computed data. Use httpResource when you want HttpClient-backed requests with minimal setup.