Preparing for a Backend Interview with Node.js & Express?

Backend Interview Questions — grouped by difficulty — to sharpen your knowledge, revise fundamentals, or challenge a friend!

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🟢 Beginner Level

1. What is Node.js and how does it work?

2. What is the difference between CommonJS and ES Modules?

3. How do you initialize a Node.js project?

4. What is npm and how is it used?

5. What is Express.js and why is it commonly used with Node.js?

6. What is middleware in Express?

7. How do you handle routing in Express?

8. What is the difference between req.params, req.query, and req.body?

9. How do you send a JSON response from an Express route?

10. How do you handle errors in Express?

🟡 Intermediate Level

1. What is the Event Loop in Node.js?

2. What are Streams in Node.js and when should you use them?

3. What is the difference between synchronous and asynchronous code in Node.js?

4. How do Promises and async/await work in Node.js?