Top 10+ Interview Questions and Answers of Node JS

  • By Sarika Ganesh Kore
  • August 24, 2023
  • MEAN Stack
Top 10+ Interview Questions and Answers of Node JS

Top 10+ Interview Questions and Answers of Node JS

1. What is Node Js? Where can you use it?

Node Js is a framework, JavaScript runtime environment, and library that is used to create server-side JavaScript applications that can be run outside the client’s browser. 

Node Js is widely used to create data-intensive applications because it uses asynchronous, event-driven programming concepts. Node Js is used to develop Real-time web applications, Network applications, General-purpose applications, and Distributed systems.

2. Why use Node Js?

While developing scalable network programs Node Js is easy to use. Some of its advantages are as follows:

  • It is fast 
  • It provides a unique programming language and various  data type
  • All the modules used in Node Js are asynchronous 
  • It provides great concurrency

3. How does Node.js work?

  • Users send requests to the webserver to get some information from the web application. Requests sent by the users can be of various types which can be non-blocking or blocking:
  • Queries for requesting the data
  • Deleting particular data 
  • Editing the requested data
  • Node Js retrieves the incoming requests and adds those to the Queue to perform action on them
  • The requests are also passed one by one using the Event Loop. It checks if the requests are using any external resources or not
  • The Event Loop processes simple requests and returns the responses to the corresponding users

To process complex requests a thread is assigned to it. This thread is responsible for completing a particular blocking request by processing external resources, such as computation, database, file system, etc.

When the task is completed, the response is given to the Event Loop which sends that response is again back to the user.

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4. Why is Node Js Single-threaded?

Node Js is single-threaded while asynchronous processing. Asynchronous processing on a single thread in Node Js provides redundant performance and scalability.

5. How does Node Js handle concurrency?

The Node JS Processing system frequently uses a JavaScript Event-based model and the JavaScript callback system. Because of it, Node Js can manage more concurrent user requests

6. Explain callback in Node Js.

A callback function is called after performing some task. Before starting the callback function it allows other code to be run and prevents blocking occurred. As an asynchronous platform, Node Js is very much dependent on callback. All the APIs created in Node are written to support callbacks.

7. Why promises are used more often instead of callbacks?

  • It provides the control inflow of asynchronous concepts in a more specified and structured way.
  • The coupling is low.
  • It provides predefined error handling.
  • It provides very good readability.

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8. How would you define the term I/O? 

  • To transfer data from one medium to another medium I/O is used in Node Js
  • Each transfer of data is an output from one medium and an input into another. 

9. How is Node.js most frequently used?

Node Js is frequently used in the following applications:

  1. Real-time chat applications
  2. Internet of Things
  3. Complex Single-Page Applications
  4. Real-time collaboration tools
  5. Streaming applications
  6. Microservices architecture

10. What is NPM?

NPM is called Node Package Manager, and it is used to manage all the packages and modules for Node Js.

Node Package Manager provides the following functionalities:

  • It provides searchable repositories for node.js packages or modules, those  are available on “
  • It provides a command-line interface to install Node Js packages and also manages Node Js versions and dependencies  

11. What are the modules in Node Js?

Modules in Node Js are like JavaScript libraries which can be used in a Node Js web application to include a set of functions. To include a module in a Node Js web application, use the require() method where you have to include the module’s name in the brackets.

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12. Why Exports module is used in Node Js?

In Node Js, a module combines all related code blocks into a single unit of code which can be parsed by including all relevant functions into a single file. You can export a module within the module and export the method, which lets it be imported into another file with a demanded keyword.

13. Why Node Js is more popular than the backend technologies like Java and PHP?

Following are the reasons why Node Js is more powerful:

  • Node Js is veritably fast
  • Node Package Manager has over 50,000 packets available at the developer’s disposal
  • More synchronization of code between server and user due to the same code base
  • Easy for web developers to start using Node Js in their applications as it is a JavaScript library

14. Most of the time which database is used with Node.js?

Most of the time MongoDB database is used with Node.js. MongoDB does not use SQL, and it is a cross-platform, document-based database that provides high performance, high availability, and easy scalability.

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Sarika Ganesh Kore

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