48 Best Node js Interview Questions (2021)

Ajay Ohri


This list has Node js interview questions compiled to help the understanding of Node.js better. There are questions batched into various levels and based on the various areas like the API, Express js, backend and such questions popular with interviewers. Work on the Intermediate and Advanced level answers to be always prepared for Node.js.

  1. Beginner Node js Interview Questions
  2. Intermediate Node js Interview Questions
  3. Advanced Node js Interview Questions

1. Beginner Node js Interview Questions

Beginner Node js interview questions are normally straightforward questions covering the basics, how and why one uses Node.js, examples of such applications, its components, definitions and the differences between front end and client end servers. Having explored the scope of such questions, interviewers always love to add their own twist and link all Node interview questions to their own specific industry. No matter how the Node js backend is worded, it is always about the basics and being extremely popular Node.js questions always are part of the interview process. So take a look at the list and learn to answer them with confidence. 

1. Explain Node.js and its uses?

2. Why would one use Node.js?

3. Explain Node.js working?

4. Why is Node.js Single-threaded?

5. What is Node.js callback?

6. What is I/O? 

7. Explain Node.js uses?

8. What are the backend and frontend development differences? 

9. What is NPM?

10. What are the modules in Node.js?

11. With backend technologies like PHP or Java, why the preference for Node.js?

12. What difference are present between Node.js and Angular?

13. Name the database used typically with Node.js?

14. What are Node js’s popularly used libraries?

15. What are Node.js advantages and disadvantages?

16. What command is required for external libraries to be imported?

2. Intermediate Node js Interview Questions

The Node.js platform, which works on the server-side of the platform, has more organizations using it for its extreme flexibility, support of browsers and applications alike. Changing career’s and getting a job is always interview-based to probe one’s extent of knowledge and whether one can apply the learning well via Express js interview questions. This is coupled with good presentation skills, intervAt the intermediate level of questions, and one can expect to be probed on Node.js application skills and API interview questions too. Here’s a list of Node js interview questions to brush up on those interview skills.

17. Explain the meaning of event-driven programming?

18. Explain the Node.js Event Loop?

19. Explain the EventEmitter function in Node.js?

20. Explain the kinds of Node.js API functions?

21. Explain the operation of the file package.json?

22. How does the URL module work in Node.js?

23. Explain what is meant by the packaged Express.js?

24. How does one create a simple application in Express.js?

25. Explain Node.js streams?

26. When working with dependency, how is it updated, installed and deleted?

27. To return the expression Hello World, create a simple Node.js server?

28. What is meant by non-blocking and asynchronous Node.js APIs?

29. Explain the implementation of Noe.js’s async?

30. Explain what is meant by module.exports and their purpose?

31. Explain the Node.js callback function?

3. Advanced Node js Interview Questions

The advanced Node js interview questions assume one has a working knowledge of Node.js, and hence the js interview questions are of a level that checks implementation at a higher level. The questions tend to be on the implantation of Node.js and typically include questions on flags, Node js Express interview questions, buffers, control and management functions in Node.js and more. Take a look at the list below.

32. Explain Node.js’s REPL functioning? 

33. Explain what is meant by the control flow function?

34. How are function calls managed by the control flow function?

35. Explain the differences between spawn() and fork() methods in Node.js?

36. Explain the Node.js buffer class?

37. What is Node.js piping?

38. How does one flag the files read/write operations?

39. Explain file opening in Node.js?

40. What is called the callback hell in Node.js?

41. Explain the Node.js reactor pattern?

42. What is the Node.js test pyramid?

43. Explain exit codes in Node.js?

44. What is the Node.js concept about middleware?

45. Explain the different kinds of HTTP requests?

46. How does one connect Node.js to a MongoDB database?

47. Explain what is NODE_ENV and its purpose?

48. Explain the various kinds of timing features in Node.js?

  • Here’s a summary of Nodejs tutorials to help with the Node js interview questions. 

Node.js, the platform on the server-side, was built and introduced by the V8 Engine, which is a JavaScript Engine on Google Chrome.

In 2009, Ryan Dahl developed the software, and its present version is v0.10.36. It is a cross-platform open-source runtime-environment for developing networking applications and the server-side. Applications in Node.js use JavaScript. It is compatible with Node.js runtime running on Microsoft Windows, Linux and OS X. It also has a variety of modules in JavaScript that help develop web applications. Node.js is extremely popular in web development and server-side development in today’s world.

Software architects love Node.js for the following reasons. 

  • Node.js is extremely fast – It uses the V8 JavaScript Engine on Google Chrome to achieve its speed in code execution.
  • It is Event-Driven and Asynchronous – The Node.js library APIs are non-blocking, meaning asynchronous. This means the server working on Node.js does not wait for the return data from the API. Instead, the server moves on after calling the API. The Events of Node.js and the mechanism of notification helps the Node.js server obtain a response from the API’s previous call.
  • Node.js never buffers – Data used by the Node.js applications is never buffered and is outputted in the form of data chunks.
  • Node.js is scalable and single-threaded − Node.js uses event looping with a single thread. The Event mechanism uses the non-blocking method to aid the server’s response making it easy to scale when compared to traditional servers with limited request threads. The single-threaded Node.js loops the program and allows it to serve a large number of requests when compared to the Apache HTTP Server, which is a traditional server.
  • License agreements – MIT holds the license for the Node.js software.

Some of the companies that use Node.js are General Electric, eBay, GoDaddy, PayPal, Microsoft, Uber, Yahoo!, Yammer, Wikipins etc. It is the technology partner for various applications like Data Streaming Applications, I/O bound Applications, SPAs- Single Page Applications, JSON APIs based Applications and DIRT- Data Intensive Real-time Applications. The only time one should not use Node.js is when the application is CPU intensive.


Learning is a process that is constantly being upgraded, and one of the best ways to revise concepts of Node.js is to prepare listicles of Node js interview questions and answer them just before one goes for the interview. It is best to write the Node js interview questions down to help revise Node js interview questions and answers, concepts, definitions, and typical questions like the one given above.

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