Question 1

How do you make HTTP calls in Angular?

Accepted Answer

Inject HttpClient and call get/post/put/delete which return Observables. Provide HttpClient via provideHttpClient(). Prefer typed responses. Handle errors with catchError. Unsubscribe or use firstValueFrom carefully.

Question 2

Why should you not subscribe in services just to store data?

Accepted Answer

Prefer returning Observables/signals to callers; services that subscribe hide cancellation and create leaks. Expose cold Observables or signal stores updated intentionally. Let components/async pipe manage subscription lifetime.

Question 3

How do you handle HTTP errors consistently?

Accepted Answer

Use interceptors for cross-cutting error mapping and catchError in feature pipelines for local recovery. Normalize error shapes. Don't swallow errors silently. Retry only idempotent GETs with backoff.

Question 4

What does HttpClient observe: 'response' vs 'events' give you?

Accepted Answer

Full HttpResponse including headers/status, or upload/download progress events. Default observe body only. Use events for progress bars. Type the generic for body.

Question 5

How do you cancel an in-flight HTTP request when navigating away?

Accepted Answer

Unsubscribe (async pipe / takeUntilDestroyed) or switchMap in a stream that completes on destroy. HttpClient aborts when unsubscribed. switchMap cancels previous searches. Don't leave orphan subscriptions.

HTTP Angular Interview Questions

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