Interview practice by role
Node.js Developer Interview Practice
Node.js interviews start with the event loop and move to API design, data stores and scaling a single-threaded runtime. Interviewers listen for whether you understand what blocks the loop.
200 practice questions5 topics5 typical rounds
How the interview usually runs
Loops differ by company. Treat this as a common pattern, not a fixed format.
- 01Screening callYour Node.js experience, frameworks and the traffic your services handled.
- 02Runtime deep diveThe event loop, promises, streams, buffers and handling errors in async code.
- 03API and data designREST design, authentication, validation, database choice and caching.
- 04Scaling and reliabilityClustering, queues, rate limiting, graceful shutdown and observability.
- 05Behavioural roundA production incident, code review practices and working with frontend teams.
What interviewers probe
- What blocks the event loop and how you avoid it
- Error handling across promises and async functions
- Authentication, sessions versus tokens and rate limiting
- Choosing between SQL and a document store
- Scaling beyond one process and keeping services observable
Common mistakes
- Calling Node fast without explaining the single-threaded trade-off
- Leaving unhandled promise rejections out of the design
- Putting heavy CPU work on the main thread
Practice questions for Node.js Developer interviews
A starting set from each topic. Every question has a short answer, the full reasoning and the follow-ups interviewers ask.
01How does the Node.js event loop work?Mediumevent loop · libuv · async02Is Node.js single-threaded? What does that actually mean?Mediumnodejs · concurrency · libuv03How do you handle errors in a Node.js backend?Mediumerror handling · async · reliability04What is a closure in JavaScript?Mediumscope · lexical environment · functions05How does this work in JavaScript?Mediumthis · functions · call site06What is hoisting in JavaScript?Mediumhoisting · scope · execution context07What is the difference between interfaces and type aliases?Mediuminterfaces · type-aliases · declaration-merging08What are intersection types?Mediumintersections · composition · type-system09How do enums work and when should you use them?Mediumenums · runtime · state10What does the CAP theorem actually say?Mediumcap theorem · consistency · partition tolerance11How does eventual consistency work and how do you handle it?Mediumeventual consistency · replication · session guarantees12How do wide-column stores organise data?Mediumwide-column · cassandra · partitioning13How does load balancing work and how do you choose an algorithm?Mediumload balancing · l4 · l714How does database sharding work and what are the pitfalls?Mediumsharding · partitioning · hotspots15How does database replication work and what consistency issues does it create?Mediumreplication · replication lag · failover
Reading is step one
Now say it out loud.
Understanding an answer and delivering it under pressure are different skills. Rehearse this topic in a live Node.js Developer mock interview and get scored feedback on depth, clarity and confidence.