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Top 10 Interview Questions & Answers for a NodeJs Developer

Costanza Tagliaferri
Researcher and technical writer - - - 3 min. to read

NodeJs’s popularity blew up because it allows the automatic increase of multiple projects during the development stage. So the job demand increased as well.

In web development, you can use the Node.js platform to scale inputs from many people across multiple machines and, in some cases, multiple data centers. In short, a web application built with Node.js allows a real-time connection between the user and server with a free exchange of data and input. Because it’s written in JavaScript, it easily connects with diverse databases working smoothly in Microsoft environments and open-source operating systems. 

To sum up, in business solutions you can use Node.js for:

  • Backend for Social Media Networking
  • Single-page Application
  • ChatBot Application
  • Data Streaming
  • IoT Application

Are you on the hunt for a new NodeJs developer and don’t know where to start? identifying the best developers depends on how good your recruitment and interviewing processes are. Here are the top 10 interview questions to get you started.

Best Interview Questions for Remote NodeJs Developers

 1. What’s the difference between JavaScript and Node.js?

TypeProgramming LanguageInterpreter and environment for JavaScript
UtilityUsed for any client-side activity for a web applicationUsed for accessing or performing any non-blocking operation of any operating system
Running EngineSpider monkey (FireFox), JavaScript Core (Safari), V8 (Google Chrome), etc.V8 (Google Chrome)

2. Best benefits of using Node.js?

FastGoogle Chrome’s V8 JavaScript Engine makes Node.Js library very fast in code execution.
AsynchronousNode.js based server never waits for an API to return data making it asynchronous.
ScalableIt is highly scalable because of its event mechanism which helps the server to respond in a non-blocking way.
Open SourceNode.js has an extensive open-source community producing modules to add additional capabilities to Node.js applications.
No BufferingNode.js applications simply output the data in chunks without buffering any data.

3. Difference between Angular and Node.js? And why do you need a basic Angular understanding?

As a Node.js developer, I need a basic understanding of Angular because I will be in charge of backend systems that will require the integration of front-end elements. 

1. It is an open source web application development framework1. It is a cross-platform run-time environment for applications
2. It is written in TypeScript2. It is written in C, C++ and JavaScript languages
3. Used for building single-page client-side web applications3. Used for building fast and scalable server-side networking applications
4. Angular itself is a web application framework4. Node.js has many different frameworks like Sails.js, Partial.js, and Express.js, etc.
5. Ideal for creating highly active and interactive web apps5. Ideal for developing small size projects
6. Helpful in splitting an app into MVC components6. Helpful in generating database queries 
7. Suitable for developing real-time applications 7. Suitable in situations where something faster and more scalable is required

4. What is REPL in the context of Node.js?

REPL in Node.js stands for Read, Eval, Print, and Loop. It represents a computer environment with a command and output system. Coming in Node.js by default, REPL can perform the below-listed tasks:

  • Read: Reads the user’s input, translates it into JavaScript data-structure, and stores it in the memory.
  • Eval: Receives and evaluates data structures
  • Print: Prints the outcome
  • Loop: Loops commands until CTRL+C is pressed twice.

5. List down the tasks you can do asynchronously using the event loop?

– I/O operations

– Heavy computation

– Anything requiring blocking

6. What is an error-first callback?

In Node.js, an error-first callback passes errors and data. So, an error object is the first parameter you need to pass to these functions. Other parameters represent associated data. You can pass the error object for testing the system, and if you don’t report any issue, you can just go ahead and with the subsequent arguments.

1234567var myPost = new Post({title: ‘edureka’});,myInstance){if(err){//handle error and return}//go ahead with `myInstance`});

7. What is the purpose of module.exports? Please give an example.

A module encapsulates all the related codes into a single unit of code, which can be interpreted by shifting all related functions into a single file. 

As example, imagine a file called greet.js containing two functions:

1234567module.exports = {greetInHindi: function(){return “NAMASTE”;},greetInKorean: function(){return “ANNYEONGHASEYO”;}};

Module.exports provide two functions which can be imported in another file using this code:

123var eduGreets = require (“./greet.js”);eduGreets.greetInHindi() //NAMASTEeduGreets.greetInKorean() //ANNYEONGHASEYO

8. What is callback hell?

Callback Hell, also known as the Pyramid of Doom, is a pattern caused by intensively nested unreadable callbacks. Usually, a callback hell contains multiple nested callback functions, making it hard to read and debug following improper implementation of the asynchronous logic.


9. Difference between spawn() and fork() methods in Node.js?

In Node.js, the spawn() is used to launch a new process with a provided set of commands without creating a new V8 instance but copying the node module active on the processor. You can use this method when your child process collects a large amount of data.


1child_process.spawn(command[, args][, options])

The fork() is a special instance of spawn() able to execute a new instance of the V8 engine with multiple workers running on a single Node code base for various tasks.


1child_process.fork(modulePath[, args][, options])

10. What are global objects in Node.js?

In NodeJs, global objects can be modules, functions, strings, objects, etc. Therefore, they are available in all the modules of the application for immediate use. Some of these objects can be in the module scope instead of the global scope.

Where to Find the Best Node.js Developers? DistantJob can Help You

Now you know what NodeJs is about and who you need to boost your business. After that, what type of employee are you looking for? A freelancer to help you with a project? Or a full-time employee for longer collaborations?

All these options can be great, it just depends on what you are looking for in your project. So, think about the person you would want in your team and get started with your hiring process to find the best NodeJs developer! 

If you don’t have the time and energy to go through the recruiting process, we are here! As a remote recruitment agency with over a decade of experience, we have helped companies successfully hire remote NodeJs developers. We are always here to share practical advice and with our unique method to find the best fit for your team in 2 weeks – try us out!

Costanza Tagliaferri

Costanza Tagliaferri, a researcher located in Italy, brings a unique blend of continental philosophy and art & visual culture from Radboud University to her role as a content writer at our IT staffing agency, DistantJob. Specializing in digital art and creative coding, she explores technology beyond its commodification, focusing on playfulness in digital techniques. At DistantJob, she specializes in articulating complex tech concepts, particularly in IT recruitment and programming languages.

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