Top 25 Node JS Interview Questions and Answers

Node.js is a well-known server-side platform that an ever-increasing number of organizations are using. On the off chance that you are planning for a career change and have an upcoming job interview, it’s a consistently smart idea to get ready and brush up on your interview questions in advance. Despite the fact that there are commonly asked Node.js interview questions that spring up during a wide range of interviews, we likewise suggest that you plan by focusing on exclusive questions to your particular industry

Node.js is a server-side scripting tool utilized by millions of developers around the globe. It is basic and has a very low learning curve. Node.js is a platform based on Chrome’s JavaScript runtime that is equipped for building anything directly from basic command programs to complex web applications. This is the reason numerous organizations have begun using Node.js as a scripting language to deal with the server-side

Huge enterprises, for example, IBM, LinkedIn, Groupon, GoDaddy, Netflix, Paypal, and numerous others are using Node.js. The immense interest and adaptable highlights of Node.js have made huge open doors for Certified Node.js engineers. Let’s get into the top NodeJs interview questions.

Below referenced is the list of top Node js interview questions and answers that will help you in cracking the interview and finding your fantasy job.

General Node JS Interview Questions and Answers

We have incorporated a comprehensive list of normal Node.js interview questions that surface regularly in interviews and the most ideal approaches to respond to these questions. This will likewise assist you with understanding the crucial ideas of Node.js.

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1. What is Node.js?

Node.js is a very famous scripting language that is principally used for server-side scripting necessities. It has various advantages compared with other server-side programming languages out there, the most essential one being the non-blocking I/O.

2. Why use Node.js?

Node.js makes building adaptable network programs simple. A portion of its preferences include:

  • It is commonly quick
  • It rarely blocks
  • It gives a uniform programming language and data type
  • Everything is nonconcurrent
  • It yields incredible concurrency

3. Quickly clarify the working of Node.js.

Node.js is an entity that runs in a virtual environment, using JavaScript as the essential scripting language. It uses a basic V8 environment to run on, which helps in the arrangement of highlights like the non-blocking I/O and a single-threaded event loop.

4. For what reason is Node.js Single-threaded?

Node.js is single-threaded for async handling. By doing async handling on a single-thread under typical web loads, more performance and adaptability can be accomplished rather than the average thread-based usage.

5. What are the various API functions upheld by Node.js?

There are two kinds of API functions. They are as per the following:

Synchronous APIs: Used for non-blocking functions
Asynchronous APIs: Used for blocking functions

6. Clarify callback in Node.js.

A callback function is called after a given assignment. It permits other codes to be run meanwhile and prevents any blocking. Being an asynchronous platform, Node.js vigorously depends on callback. All APIs of Node are written to help callbacks.

7. What are significant variations between Angular and Node.js?

Angular Node.js
It is a frontend development framework It is a server-side environment
It is written in TypeScript It is written in C, C++ languages
Best reasonable for creating single-page applications. Generally used for the development of server-side systems networking applications.
Angular is an all-in-one web app framework Gives numerous frameworks, for example, Sails, Partial, and Express
Capacity to simplify an application into the MVC design Capacity to generate questions in a database

8. Which database is all the more prominently used with Node.js?

MongoDB is the most widely recognized database used with Node.js. It is a NoSQL, cross-platform, document-oriented database that gives high performance, high accessibility, and simple scalability.

9. What are probably the most commonly used libraries in Node.js?

There are two normally used libraries in Node.js:

ExpressJS – Express is an adaptable Node.js web application framework that gives a wide arrangement of highlights to create web and mobile applications.

Mongoose – Mongoose is likewise a Node.js web application framework that makes it simple to interface an application to a database.

10. What is the control flow work?

The control flow function is a typical code snippet, which executes at whatever point there are any asynchronous functions called, and they are used to assess the request in which these functions are executed in Node.js.

Node JS Interview Questions and Answers for Experienced Professionals

11. What is the framework that is used significantly in Node.js today?

Node.js has various frameworks, to be specific:


Among these, the most used framework is Express.js for its capacity to give great versatility, adaptability, and moderation.

12. What are the security executions that are available in Node.js?

Following are the significant executions for security:

-Error handling protocols
-Authentications pipelines

13. What are worldwide objects in Node.js?

Worldwide objects are objects with a scope that is available over all of the modules of the Node.js application. There won’t be any need to remember the articles for each module. One of the objects is proclaimed worldwide. Along these lines, this is done to give any functions, strings, or objects access over the application.

14. What is an Event Loop in Node.js?

Event loops handle asynchronous callbacks in Node.js. It is the establishment of the non-blocking input/output in Node.js, making it one of the main environmental highlights.

15. What is the Express.js bundle?

Express is an adaptable Node.js web application framework that gives a wide arrangement of highlights to create both web and mobile applications

16. What is the primary difference between Node.js and Ajax?

The core difference between Node.js and Ajax is that Node.js is a server-side innovation through Ajax is a client-side innovation. To lay it out simply Ajax is generally used for changing or refreshing the content on a website page without having to refresh it. The Node.js server software can be used on the workers as opposed to web browsers.

17. What are stubs in Node.js?

Stubs are just functions that are used to assess and analyze individual component behavior. When running experiments, stubs are helpful in giving the details of the functions executed.

18. What is the use of the connect module in Node.js?

The interface module in Node.js is used to give communication between Node.js and the HTTP module. This additionally furnishes simple integration with Express.js, using the middleware modules.

19. What are the kinds of streams available in Node.js?

Node.js upholds a variety of streams, in particular:
-Duplex (both read and write)
-Readable streams
-Writable streams
-Transform (duplex for modifying data)

20. What is meant by tracing in Node.js?

Tracing is a philosophy used to gather all of the following data that gets produced by V8, the node core, and the userspace code. These are unloaded into a log document and are extremely helpful to approve and check the integrity of the data being passed.

21. What are the Challenges with Node.js?

Emphasizing the technical side, it’s a bit of a challenge in Node.js to have one cycle with one string to scale up on a multi-core server.

22. What is the use of middleware in Node.js?

A middleware is a simple function that can deal with handling incoming requests and outbound reaction objects. Middleware is utilized essentially for the following tasks:
-Execution of code (of any sort)
-Updation of request and reaction objects
-Finish of request-response interactions
-Calling the next middleware

23. Why is a buffer class used in Node.js?

A buffer class is essentially utilized as an approach to store information in Node.js. This can be considered as a similar execution of arrays or lists. Here, the class refers to a raw memory location that is absent in the V8 heap structure.
The buffer class is worldwide, in this manner broadening its usage over all the modules of an application.

24. What is the use of the module. exports in Node.js?

The module. exports function is utilized to uncover two capacities and carry them to a usable context. A module is an entity that is utilized to store relative code in a solitary snippet. This can be considered as an activity of moving all the capacities into one single record.

25. Clarify REPL in Node.js?

The REPL means “Read Eval Print Loop”. It is a basic program that acknowledges the commands, evaluates them, lastly prints the outcomes. REPL gives an environment like that of a Unix/Linux shell or window support, in which we can enter the order and the framework, in turn, reacts with the output. REPL plays out the accompanying tasks.

It reads the input from the user, parses it into a JavaScript information structure, and afterward stores it in the memory.
It Executes the data structure.
It Prints the outcome acquired after evaluating the command.
It Loops the above command until the user presses Ctrl+C multiple times.


I accept that these Node js interview questions and answers would enable you to comprehend what kind of questions might be asked to you in an interview, and by experiencing these Node.js interview questions, you can get ready and crack your next interview in one go.

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