angular-signals

Create writable state with signal(initialValue), read it by calling the signal as a function, and update it with set() or update(). Derive dependent values with computed(), which automatically recalculates when its dependencies change.

Use toSignal() from @angular/core/rxjs-interop to convert an Observable into a signal, optionally passing initialValue or requireSync for synchronous sources like BehaviorSubject. Use toObservable() to go the other direction and apply RxJS operators like debounceTime.

computed() creates read-only derived state that recalculates from its dependencies. linkedSignal() creates writable state that automatically resets when its source changes, with access to the previous value for preserving selections.

Yes, the resource() API fetches async data reactively by re-running its loader whenever params signals change, exposing value, isLoading, error, and status signals. Alternatively, combine toObservable with switchMap and convert back with toSignal.

Signals fit synchronous, fine-grained component and service state without subscription management or async pipe boilerplate. Keep RxJS for event streams requiring operators like debounce, retry, or complex composition, bridging the two with the interop functions.

Test signals by calling them as functions to assert current values, then updating with set() and re-asserting. For services using HttpClient, use provideHttpClientTesting with HttpTestingController and set the private state signal directly to test selectors.