NodeJS Interview Questions and Responses|Set 1

NodeJS is an open-source and cross-platform runtime environment developed on Chrome’s V8 JavaScript engine for performing JavaScript code beyond an internet browser. You require to remember that NodeJS isn’t a structure, and it’s not a programing language. It supplies an event-driven, non-blocking (asynchronous) I/O and cross-platform runtime environment for developing extremely scalable server-side applications utilizing JavaScript.

Node.js Interview Questions & & Responses

Let’s talk about some typical concerns that you must get ready for the interviews. These concerns will be handy in clearing the interviews specifically for the backend advancement or complete stack advancement function.

This set includes the fundamental concerns asked in the interview.

1. What is Node.js?

Node.js is a JavaScript engine utilized for performing JavaScript code outside the web browser. It is generally utilized to construct the backend of the application and is extremely scalable.

2. What is the distinction in between Node.js and JavaScript?

JavaScript is a scripting language whereas Node.js is an engine that supplies the runtime environment to run JavaScript code.

  • JavaScript: It is a light-weighted programs language (” scripting language”) utilized to establish interactive websites. It can place vibrant text into the HTML components. JavaScript is likewise referred to as the web browser’s language.
  • Node.js: It is utilized to run JavaScript programs outside the web browser and it mainly runs server-side code. It can not be utilized to run HTML tags.

3. Is Node.js single-threaded?

Yes, Node.js is a single-threaded application as it is developed utilizing the single-threaded occasion loop design architecture.

4. What type of API function is supported by Node.js?

There are 2 kinds of API functions supported by Node.js:

  • Simultaneous: These API functions are utilized for non-blocking code.
  • Asynchronous: These API functions are utilized for obstructing code.

5. What is the distinction in between Simultaneous and Asynchronous functions?

  • Simultaneous function: These are the function that obstruct the execution of the program whenever an operation is carried out. For this reason these are likewise called obstructing operations. We utilize these functions to carry out light-weight jobs
  • Asynchronous function: These are the operations that do not obstruct the execution of the program and each command is carried out after the previous command even if the previous command has actually not calculated the outcome. We utilize these functions to carry out heavy jobs.

6. What is a module in Node.js?

In Node.js Application, a Module can be thought about as a block of code that supply a basic or complicated performance that can interact with external application. Modules can be arranged in a file or a collection of numerous files/folders. Modules work due to the fact that of their reusability and capability to lower the intricacy of code into smaller sized pieces. Some examples of modules are. http, fs, os, course, and so on

7. What is npm and its benefits?

NPM represents Node Plan Supervisor. It is an online repository for Node.js bundles. We can set up these bundles in our projects/applications utilizing the command line.

8. What is middleware?

Middleware is the function that works in between the demand and the reaction cycle. Middleware gets carried out after the server gets the demand and prior to the controller sends out the reaction.

9. How does Node.js manage concurrency even after being single-threaded?

Node.js internally utilizes libuv library for dealing with all async call. This library produces numerous thread swimming pools to manage async operations.

10. What is control circulation in Node.js?

Control Circulation functions are carried out whenever there is an async call made in the program. These functions specify the order in which these asynchronous functions will be carried out.

11. What do you indicate by occasion loop in Node.js?

Occasion Loop in Node.js is utilized to manage callbacks. It is handy in carrying out non-blocking I/O operations. An occasion loop is an unlimited loop, which awaits jobs, performs them, and after that sleeps till it gets more jobs.

12. What is the order in which control circulation declarations get carried out?

The order in which the declarations are carried out is as follows:

  • Execution and line handling
  • Collection of information and keeping it
  • Managing concurrency
  • Performing the next lines of code

13. What are the primary drawbacks of Node.js?

Considering that Node.js is single-threaded so multi-threaded engines are much better and can manage jobs more effectively. Likewise, we do not utilize relational databases with Node.js like MySQL mainly non-relational databases like MongoDB is utilized.

14. What is REPL in Node.js?

REPL in Node.js represents Read, Evaluate, Print, and Loop. It is a computer system environment comparable to the shell which works for composing and debugging code as it carries out the code in on go.

15. How to import a module in Node.js?

We utilize the need module to import the External libraries in Node.js. The outcome returned by need() is saved in a variable which is utilized to conjure up the functions utilizing the dot notation.

16. What is the distinction in between Node.js and AJAX?

Node.js is a JavaScript runtime environment that operates on the server side whereas AJAX is a client-side programs language that operates on the web browser.

17. What is package.json in Node.js?

package.json is a file that is utilized to keep the metadata of all the contents of the job. It is utilized to explain the module utilized, run commands, and other beneficial details about the job.

18. How to compose hi world utilizing node.js?


const http = need(' http');

http.createServer( function ( req, res) {

res.write(' Hi World!');


} ). listen( 3000 );

Run this program from the command line and see the output in the web browser window. This program prints Hi World on the web browser when the web browser sends out a demand through http://localhost:3000/.

19. What is the most popular Node.js structure utilized nowadays?

The most well-known Node.js structure utilized is Express.js as it is extremely scalable, effective, and needs extremely couple of lines of code to produce an application.

20. What are guarantees in Node.js?

A pledge is essentially a development of callbacks in NodeJS. Simply put, a guarantee is a JavaScript item which is utilized to manage all the asynchronous information operations. While establishing an application you might come across that you are utilizing a great deal of embedded callback functions which triggers an issue of callback hell. Assures resolve this issue of callback hell.

Last Upgraded:
23 May, 2023

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