Looking for the best Node.js interview questions to ask a candidate? You’re in luck. We’ve compiled 50 of the best questions to help you get started. Node.js has been gaining popularity lately as a server-side JavaScript platform. It’s used by big companies like PayPal, Netflix, and LinkedIn.

If you’re looking to hire a Node.js developer or add one to your team, it’s important to ask the right questions. The questions you ask should test for both technical skills and soft skills.

Node.js Interview Questions

Before we dive into the best questions to ask, let’s review what Node.js is and why it’s become so popular.

What Is Node.js?

Node.js is a JavaScript platform that allows developers to write server-side code. It’s built on the V8 engine, which is used in Google Chrome. That means it’s fast and can handle a lot of traffic.

It’s event-driven, which makes it perfect for real-time applications like chatbots and games. And it has a huge ecosystem of open-source libraries, which makes development faster and easier.

Node.js is used by some of the biggest companies in the world, including PayPal, Netflix, and LinkedIn.

Why Node.js Is So Popular

There are a few reasons Node.js has become so popular.

First, it’s fast. The V8 engine compiles JavaScript code into machine code when it’s run. That means Node.js can handle a lot of traffic without slowing down.

Second, it’s event-driven. That means it can handle multiple requests at the same time. That’s perfect for real-time applications like chatbots and games.

Third, it has a huge ecosystem of open-source libraries. That makes development faster and easier because you don’t have to write everything from scratch.

Now that you know what Node.js is and why it’s popular, let’s dive into the best questions to ask a candidate.

50 Best Interview Questions to Ask First

When you’re interviewing candidates, you want to ask questions that will test both their technical skills and their soft skills.

First, let’s review some questions that will test a candidate’s technical skills.

1. What is Node.js?

Node.js is an open-source, cross-platform JavaScript runtime environment that allows developers to write server-side code. Node.js is great for real-time applications because it’s event-driven and can handle multiple requests at the same time.

2. Why use Node.js?

Node.js makes building scalable network programs easy. It’s also fast and has a huge ecosystem of open-source libraries.

3. What is the difference between Node.js and JavaScript?

Node.js is a platform that allows you to write server-side code in JavaScript. JavaScript is a programming language that is used to create websites and web applications.

4. What is the V8 engine?

The V8 engine is a JavaScript engine that is used in Google Chrome. It’s fast and can handle a lot of traffic.

5. How does Node.js work?

Node.js works by using an event-driven, non-blocking I/O model. That means it can handle multiple requests at the same time.

6. What is an event loop?

An event loop is a programming construct that allows Node.js to perform non-blocking I/O operations.

7. What are the benefits of using an event-driven architecture?

Some benefits of using an event-driven architecture are that it’s scalable and can handle a lot of traffic. It’s also perfect for real-time applications.

8. What is the difference between an asynchronous and a synchronous function?

An asynchronous function is a function that doesn’t block the main thread. A synchronous function is a function that does block the main thread.

9. What is a callback function?

A callback function is a function that is called after an asynchronous operation has completed.

10. What are the differences between Node.js and PHP?

Node.js is faster than PHP because it’s event-driven and can handle multiple requests at the same time. PHP is a synchronous language, which means it can only handle one request at a time. Node.js is also cross-platform, which means it can run on any operating system.

11. What are the differences between Node.js and Ruby?

Node.js is faster than Ruby because it’s event-driven and can handle multiple requests at the same time. Ruby is a synchronous language, which means it can only handle one request at a time. Node.js is also cross-platform, which means it can run on any operating system. Ruby is only available on Linux.

12. What are the differences between Node.js and Python?

Node.js is faster than Python because it’s event-driven and can handle multiple requests at the same time. Python is a synchronous language, which means it can only handle one request at a time. Node.js is also cross-platform, which means it can run on any operating system. Python is only available on Linux.

13. What are global objects?

Global objects are objects that are available in all modules.

14. What is a module?

A module is a JavaScript file that contains code that can be reused in other files.

15. What is the require function?

The require function is used to import modules into files.

16. What is the module.exports object?

The module.exports object is used to export modules from files.

17. What is NPM?

NPM is a package manager for Node.js modules. It can be used to install, update, and uninstall modules.

18. What is theEventEmitter class?

The EventEmitter class is a built-in class that can be used to create event-emitting objects.

19. What is a stream?

A stream is an event emitter that emits data events. Data events are emitted when data is available to be read from a stream.

20. What are the differences between streams and files?

Streams are event emitters that emit data events. Files are objects that contain data. Streams can be used to process files because they can emit data events as the file is being read.

21. What are the differences between Node.js and Java?

Node.js is faster than Java because it’s event-driven and can handle multiple requests at the same time. Java is a synchronous language, which means it can only handle one request at a time. Node.js is also cross-platform, which means it can run on any operating system. Java is only available on Linux.

22. What are the differences between Node.js and .NET?

Node.js is faster than .NET because it’s event-driven and can handle multiple requests at the same time. .NET is a synchronous language, which means it can only handle one request at a time. Node.js is also cross-platform, which means it can run on any operating system. .NET is only available on Windows.

23. What are the differences between Node.js and Go?

Node.js is faster than Go because it’s event-driven and can handle multiple requests at the same time. Go is a synchronous language, which means it can only handle one request at a time. Node.js is also cross-platform, which means it can run on any operating system. Go is only available on Linux.

24. What are the differences between Node.js and C++?

Node.js is faster than C++ because it’s event-driven and can handle multiple requests at the same time. C++ is a synchronous language, which means it can only handle one request at a time. Node.js is also cross-platform, which means it can run on any operating system. C++ is only available on Linux.

25. What are the differences between Node.js and Rust?

Node.js is faster than Rust because it’s event-driven and can handle multiple requests at the same time. Rust is a synchronous language, which means it can only handle one request at a time. Node.js is also cross-platform, which means it can run on any operating system. Rust is only available on Linux.

26. What are the differences between Node.js and Objective C?

Node.js is faster than Objective C because it’s event-driven and can handle multiple requests at the same time. Objective C is a synchronous language, which means it can only handle one request at a time. Node.js is also cross-platform, which means it can run on any operating system. Objective C is only available on MacOS.

27. What are the differences between Node.js and Swift?

Node.js is faster than Swift because it’s event-driven and can handle multiple requests at the same time. Swift is a synchronous language, which means it can only handle one request at a time. Node.js is also cross-platform, which means it can run on any operating system. Swift is only available on MacOS.

28. What are the differences between Node.js and Python?

Node.js is faster than Python because it’s event-driven and can handle multiple requests at the same time. Python is a synchronous language, which means it can only handle one request at a time. Node.js is also cross-platform, which means it can run on any operating system. Python is only available on Windows and Linux.

29. What is the purpose of the module .Exports?

The purpose of the module .Exports is to expose a Node.js module’s public API. The module .Exports is an object that contains the methods and properties that are exposed to the module’s consumers.

30. What is the purpose of the require function?

The require function is used to import modules into a Node.js application. The require function will return an object that contains the exported members of the required module.

31. What is the purpose of the __filename global variable?

The __filename global variable provides the filename of the code being executed. This can be useful for logging or debugging purposes.

32. What is the purpose of the __dirname global variable?

The __dirname global variable provides the directory name of the code being executed. This can be useful for resolving path names.

33. What is the purpose of process.exit()?

The process.exit() method will terminate a Node.js process with an exit code. This is useful for ensuring that resource cleanup routines are called before the process exits.

34. What is the purpose of setTimeout()?

The setTimeout() function is used to schedule a callback to be invoked after a delay. This can be useful for performing async tasks such as making HTTP requests or querying a database.

35. What is the purpose of clearTimeout()?

The clearTimeout() function is used to cancel a callback that has been scheduled with setTimeout(). This can be useful for cancelling async tasks that are no longer needed.

36. What is the purpose of setInterval()?

The setInterval() function is used to schedule a callback to be invoked at regular intervals. This can be useful for performing periodic tasks such as checking for new email or polling a server for new data.

37. What is the purpose of clearInterval()?

The clearInterval() function is used to cancel a callback that has been scheduled with setInterval(). This can be useful for cancelling periodic tasks that are no longer needed.

38. What is the purpose of process.nextTick()?

The process.nextTick() method is used to schedule a callback to be invoked on the next cycle of the event loop. This can be useful for deferring work until the current event loop has finished processing.

39. What is the purpose of Buffer.isEncoding()?

The Buffer.isEncoding() method is used to check if a specified encoding is supported by Node.js. This can be useful for determining if a string can be decoded with a particular encoding.

40. Which database is more popularly used with Node.js?

MongoDB is the most popular database used with Node.js. MongoDB is a document-oriented database that is well-suited for storing JSON data.

41. What are some of the popular web frameworks used with Node.js?

Express, Koa, and Hapi are some of the popular web frameworks used with Node.js. These frameworks provide a set of tools for building web applications.

42. What is the purpose of NPM?

NPM is a package manager for Node.js modules. NPM can be used to install, update, and remove Node.js modules from a computer. NPM can also be used to publish new Node.js modules to the NPM registry.

43. What is the command used to import external libraries in Node.js?

The required command is used to import external libraries in Node.js. The require command will return an object that contains the members of the required library.

44. What is the best way to structure a large Node.js project?

There is no one best way to structure a large Node.js project. However, it is generally recommended to use a modular approach where each file contains a single module. This can help to make the code more maintainable and easier to understand.

45. What are some of the best practices for debugging Node.js applications?

Some of the best practices for debugging Node.js applications include using a debugger, logging errors, and using a profiler. These tools can help to identify and fix errors in Node.js applications.

46. What is the best way to unit test a Node.js application?

Mocha is a popular unit testing framework for Node.js applications. Mocha can be used to define tests and run them against the application code.

47. What is the best way to deploy a Node.js application?

There are many ways to deploy a Node.js application. Some of the most popular methods include using PM2, using Forever, and using Upstart.

48. What is the best way to scale a Node.js application?

There are many ways to scale a Node.js application. Some of the most popular methods include adding more servers, using a load balancer, and using a caching system.

49. What are the two types of API functions in Node.js?

The two types of API functions in Node.js are synchronous and asynchronous. Synchronous functions are executed one at a time while asynchronous functions are executed in parallel.

50. What is the best way to handle errors in Node.js?

The best way to handle errors in Node.js is to use the provided Error object. The Error object can be used to create custom error messages and to track the stack trace of an error.

Final Thoughts

These are the best Node.js interview questions to ask first. Asking these questions will help you to quickly identify if a candidate has the skillset required to be a successful Node.js developer.

When interviewing candidates, it is also important to assess their ability to communicate and work effectively in a team. These skills are just as important as technical ability when it comes to being a successful Node.js developer.

The best way to find out if a candidate has these skills is to ask them questions about their previous experiences working on Node.js projects. Try to ask specific questions about their role in the project and how they interacted with other team members.

Asking these questions will help you to hire the best Node.js developers for your team.

Do you have any other suggestions for Node.js interview questions? Let us know.