angular-rxjs-patterns

Use Angular's HttpClient, which returns observables for get, post, put, and delete operations. Pipe the results through operators like map, catchError, and retry, then subscribe in components or expose them to templates with the async pipe.

Use takeUntilDestroyed from @angular/core/rxjs-interop, which automatically unsubscribes when the component is destroyed without needing ngOnDestroy. Alternatively, use the async pipe in templates or DestroyRef for imperative subscriptions.

switchMap cancels the previous inner observable when a new value arrives, ideal for search inputs. mergeMap runs all inner observables in parallel, while concatMap queues them and executes sequentially, preserving order.

Prefer signals for synchronous state in modern Angular, using computed for derived values. Use BehaviorSubject when you need observable streams, and convert observables to signals with toSignal when rendering async data in templates.

Use the retry operator for a fixed number of attempts, or retryWhen combined with delay and take for delayed retries. For exponential backoff, use retryWhen with mergeMap to compute increasing delays based on the attempt index.

Cold observables like HttpClient requests execute once per subscription, so multiple subscribers trigger duplicate requests. Apply shareReplay(1) to cache the last emitted value and share a single execution across all subscribers.