Asynchronous JavaScript — Fetch. Await. Master.
Build rock-solid async skills with topic-wise assignments. Each set includes 20 Basic, 20 Intermediate, and 10 Advanced questions so learners move from callbacks to production-ready concurrency, cancellation, and resilience patterns.
Why practice with these assignments?
- Go beyond theory—simulate latency, failures, retries, and streaming.
- Internalize the event loop, task queues, and microtask vs macrotask behavior.
- Master Promises and async/await with real API scenarios and edge cases.
- Prepare for interviews and real projects with tasks that mirror day-to-day work.
How it works
- Pick a topic from the list.
- Attempt questions in order: Basic → Intermediate → Advanced.
- Run in the browser and/or Node; observe with DevTools and logs.
- Add timeouts, retries, and cancellation—then measure outcomes.
- Save your best solutions as portfolio-ready snippets and mini-demos.
What you’ll achieve
- A clear mental model of how JS schedules and runs async tasks.
- Confidence with Promises, async/await, combinators, and cancellation.
- Practical skills for networking, streaming, files, and background work.
- Production habits: timeouts, retries with backoff, idempotency, and tests.
Who should use this page?
JavaScript beginners leveling up, interview candidates, and front-/back-end developers who need dependable async code in apps, APIs, and tooling.
Tips for success
- Prefer async/await for readability; use combinators for structured parallelism.
- Always add timeouts and cancellation—no request should run forever.
- Keep side effects idempotent; guard against duplicate submissions.
- Limit concurrency; queue work and apply backoff on failure.
- Don’t mix callbacks and promises in the same API—wrap once, use consistently.
- Test the sad paths: timeouts, aborts, partial responses, network flakiness.
- Log timings (start/end) to see real-world latency and drift.
Ready to build real confidence in Asynchronous JS? Pick a set below and start solving!
FAQs
Q1. Browser or Node?
Both. Topics indicate when a task is browser-only or Node-only—many work in either.
Q2. Do I need a real server?
No. Use public APIs or mock with MSW/Nock; simulate latency/failures locally.
Q3. How do I verify correctness?
Use DevTools (Network/Performance/Console), fake timers, and assertions that check timeouts, retries, and cancellation behavior.
Q4. Are there solutions?
Selected topics include reference implementations and alt approaches—review after attempting.
Q5. How much time should I spend?
Plan 10–40 minutes per difficulty band per topic; streaming and Node workers may take longer.