Node.js Interview Questions for 3 Years Experience

What interviewers expect at ~3 years

Around three years of experience, interviewers want clear fundamentals and evidence you have shipped APIs, not only tutorials. You should explain the event loop, promises, Express middleware, basic SQL or Mongo usage, and how you debug production issues. You are not expected to design a global multi-region platform cold, but you should reason about indexes, timeouts, and error handling.

Core topics to master

• Event loop, nextTick, promises, async/await
• Express routing, middleware, and error handlers
• REST design, validation, auth basics (JWT/sessions)
• SQL queries, indexes, and connection pooling basics
• Logging, environment config, and simple performance fixes

Sample questions and answer angles

Q: How does async/await relate to the event loop? A: await yields the async function until the Promise settles; other callbacks can run meanwhile. It does not create a new thread.

Q: How do you handle errors in Express? A: Forward with next(err), use a four-argument error middleware, and avoid sending twice. Async handlers need try/catch or a wrapper.

Q: Why use a connection pool? A: Creating a DB connection per request is slow; a pool reuses warm connections and must release them on every path.

Practice plan

Spend one week on runtime fundamentals, one on APIs and data, then run three HireReadyAI Node.js mocks. After each mock, write the weakest topic and study only that the next day.