Top 50+Nodejs Interview Question and Answer 2024

Ideas earlier than you attend Node.JS an interview

  • Put together for frequent interview questions which we’re going to discuss on this weblog. 
  • Earlier than you try any interview ensure you ought to analysis the corporate’s background, it’s going to assist communication between you and the interviewee.
  • Be certain that your GitHub repository has a mission and an open-source contribution on it, an empty repository is an indication of a foul developer.
  • Be certain that your LinkedIn profile is effectively maintained too.
  • Present your Management expertise.
  •  Observe your answering expertise with another person or in entrance of a mirror
  • Take into consideration your Strengths as a result of these are FAQs
  • Point out a selected accomplishment or exercise that matches the responsibility.
  • Give legit, easy solutions.
  • Carry a replica of your resume for every assembly.
  • Be certain that are updated with present information.

Node.js is a standard server-side platform utilized by many corporations. If you’re making ready for a profession change, it’s all the time a good suggestion to brush up in your interview expertise beforehand. Though there are a couple of generally requested Node.js interview questions that you simply would possibly concentrate on, we additionally advocate you to deal with unique Node.js interview questions.

We now have compiled a listing of Node.js interview questions that come up typically in interviews and in addition enable you perceive the elementary ideas of Node.js.

Newbie’s NodeJS interview questions

1) What’s nodeJS

NodeJS or node is an open-source and cross-platform runtime surroundings that’s constructed on Chrome’s V8 engine (which is written in c++) for executing JavaScript code exterior of the browser.

JavaScript runs within the browser it will possibly solely entry your net web page however if you enable it to run in your machine with NodeJS we simply created an entire new world the place js can entry the file system, Occasions, OS, and different methods core module.

usually, we use to construct back-end providers or API additionally known as (software programming interfaces) these are the providers that energy our shopper purposes like an internet app operating within an internet browser or a cell software.

Corporations like’s Netflix, LinkedIn, Uber, and plenty of extra makes use of nodeJS js for managing their providers.

So at present javaScript can also be a back-end in addition to the front-end programming language.

2) What are the info varieties in Node.js? Primitive Sorts.

Nodejs is constructed on prime of JavaScript so a lot of the information kind that current in JavaScript can also be current in Nodejs.

String -> It comprise set of characters that may additionally comprise areas and numbers for instance 

          const string1 = “A string primitive”;

          const string2 = ‘i’m string too’;

          const string3 = `quantity like 1,2,3 are additionally a instance of string`; 

Quantity → by default each worth is float information kind.

const num = 2;

Boolean → true or false.

const num = true;

const num2 = false;

Undefined → worth if not assigned to the variable.

const num; // num is undefined.

Null → absence of object worth.

nodejs has another further information kind which isn’t accessible within the browser’s JavaScript

Buffer →  Buffer is principally used to retailer binary information.

3) What’s callback hell in Node.js?

Callback hell is an occasion when a developer tries to execute a number of asynchronous operations one after the opposite.

aync_Callback1(perform () {

  aync_Callback2(perform () {

    aync_Callback3(perform () {

      aync_Callback4(perform () {

    })

  })

})

4) How are you going to stop CallBack hell?

Strategies for avoiding callback hell

Utilizing Async.js 

is a highly regarded utility module for dealing with Asynchronous callbacks.

Additionally, this utility module is obtainable for JavaScript.

Async.js ->  https://www.npmjs.com/package deal/async 

command -> npm set up async

Utilizing Guarantees

Guarantees provide an affiliate an alternate solution to write async code. They both come the outcomes of execution or the error/exception. Implementing ensures wants the utilization of <.then()> carry out that waits for the promise object to return. It takes 2 nonobligatory arguments, every perform. trying on the state of the promise simply one among them can get known as. the first name payoff if the promise will get consummated. Nonetheless, if the promise will get rejected, then the second efficiency can get known as.

5) Are you able to entry DOM within the node?

 No, you can’t entry DOM(doc object mannequin) in node.  

6) When Ought to We Use Node.Js?

-> NodeJS is usually used after we are constructing methods that require a excessive variety of I/O operations. Like saving information to DataBase, information entry. 

For instance :

  • IoT Purposes
  • Video Streaming.
  • Chat purposes.
  • Sport servers.
  • Commercial Servers

7)  What’s Globals in NodeJS? with instance

->  object akin to __filename, __dirname, setTimeout(), setInterval() and many others are some instance of World in nodejs. An object which exists in scope module, so we don’t have to incorporate these object in our software.

    __filename instance:-

    print the file title of present module

     console.log(__filename); 

    /nodeJS-WorkSpace/project-1/index.js

    __dirname instance:-

   print the listing title of the present mission.

    console.log(__dirname); 

    /nodeJS-WorkSpace/project-1

8)  What are essentially the most generally used HTTP Request Strategies?

a very powerful and customary HTTP Request Strategies are GET,POST, PUT, DELETE   are used to carry out CRUD (Create, Learn, Replace and Delete) operations in DataBase.

    GET -> Request and retrieve information from server.

    POST -> POST requests are make the most of to ship information to a server to create or replace or overwrite   a useful resource.

    frequent instance is after we add a photograph.  

    PUT -> if you wish to modify a selected a part of useful resource, which is already a component   of    useful resource assortment.

    PATCH -> PATCH technique provides a set of directions to switch the useful resource.       PATCH is NOT idempotent.

    DELETE -> as title says DELETE will delete useful resource from server.

9) What’s the MERN stack?

Stack is assortment of software program.

MongoDB -> NoSQL which stands for non relation database.

👉 https://www.mongodb.com/what-is-mongodb (official web site)

Specific.js -> The default net purposes framework.

👉 https://expressjs.com/  (official web site)

REACT.js -> React an open-source, entrance finish, JavaScript library for constructing consumer       interfaces.

👉 https://reactjs.org/ (official web site)

Node.js -> nodejs is an open-source and cross-platform constructed on Chrome’s V8 engine constructed by Ryan Dahl for executing JavaScript code exterior of the browser.

👉https://nodejs.org/en/  (official web site)

10) Are you able to console all HTTP standing code in NodeJS?

sure we are able to console all HTTP standing code.

first we’ve got to require a HTTP module from nodejs.

After that we are able to now use HTTP module within our program.

Now we’ve got to kind following code

 console.log(http.STATUS_CODES) 

The above command will give following Object which look one thing like this

STATUS_CODES: {

    ‘100’: ‘Proceed’,

    ‘101’: ‘Switching Protocols’,

    ‘102’: ‘Processing’,

    ‘103’: ‘Early Hints’,

    ‘200’: ‘OK’,

    ‘201’: ‘Created’,

    ‘202’: ‘Accepted’,

    ‘203’: ‘Non-Authoritative Data’,

    ‘204’: ‘No Content material’,

    ‘205’: ‘Reset Content material’,

    ‘206’: ‘Partial Content material’,

    ‘207’: ‘Multi-Standing’,

    ‘208’: ‘Already Reported’,

    ‘226’: ‘IM Used’,

    ‘300’: ‘A number of Decisions’,

    ‘301’: ‘Moved Completely’,

    ‘302’: ‘Discovered’,

    ‘303’: ‘See Different’,

    ‘304’: ‘Not Modified’,

    ‘305’: ‘Use Proxy’,

    ‘307’: ‘Short-term Redirect’,

    ‘308’: ‘Everlasting Redirect’,

    ‘400’: ‘Unhealthy Request’,

    ‘401’: ‘Unauthorized’,

    ‘402’: ‘Fee Required’,

    ‘403’: ‘Forbidden’,

    ‘404’: ‘Not Discovered’,

    ‘405’: ‘Methodology Not Allowed’,

    ‘406’: ‘Not Acceptable’,

    ‘407’: ‘Proxy Authentication Required’,

    ‘408’: ‘Request Timeout’,

    ‘409’: ‘Battle’,

    ‘410’: ‘Gone’,

    ‘411’: ‘Size Required’,

    ‘412’: ‘Precondition Failed’,

    ‘413’: ‘Payload Too Giant’,

    ‘414’: ‘URI Too Lengthy’,

    ‘415’: ‘Unsupported Media Kind’,

    ‘416’: ‘Vary Not Satisfiable’,

    ‘417’: ‘Expectation Failed’,

    ‘418’: “I’m a Teapot”,

    ‘421’: ‘Misdirected Request’,

    ‘422’: ‘Unprocessable Entity’,

    ‘423’: ‘Locked’,

    ‘424’: ‘Failed Dependency’,

    ‘425’: ‘Too Early’,

    ‘426’: ‘Improve Required’,

    ‘428’: ‘Precondition Required’,

    ‘429’: ‘Too Many Requests’,

    ‘431’: ‘Request Header Fields Too Giant’,

    ‘451’: ‘Unavailable For Authorized Causes’,

    ‘500’: ‘Inside Server Error’,

    ‘501’: ‘Not Applied’,

    ‘502’: ‘Unhealthy Gateway’,

    ‘503’: ‘Service Unavailable’,

    ‘504’: ‘Gateway Timeout’,

    ‘505’: ‘HTTP Model Not Supported’,

    ‘506’: ‘Variant Additionally Negotiates’,

    ‘507’: ‘Inadequate Storage’,

    ‘508’: ‘Loop Detected’,

    ‘509’: ‘Bandwidth Restrict Exceeded’,

    ‘510’: ‘Not Prolonged’,

    ‘511’: ‘Community Authentication Required’

}

11) What’s node js used for?

Once we try to construct methods which has a excessive variety of request and response cycle. Like saving information to Knowledge Base, information entry.

Nodejs might be use in lots of software like.

  • The back-end for Social Media Networking
  • Single-page Utility
  • Chat Utility
  • Knowledge Streaming
  • IoT Utility
  • Video Streaming

13) What’s npm in node js?

npm is that the default package deal supervisor for the JavaScript runtime environment Node.js. It consists of an announcement shopper, moreover known as npm, and web info of public and paid-for private packages, known as the npm written file. The written file is accessed by way of the patron, and in addition the accessible packages shall be browsed and searched by way of the npm web site. The package deal supervisor and in addition the written file space unit managed by npm, Inc

  • It really works as an internet repository for node.js packages/modules which might be discovered on https://www.npmjs.com/.
  • It really works as a Command-line utility to put in packages bundles.

NodeJS is standard for a lot of causes akin to:-

-> NodeJS is quicker examine to different back-end languages.

-> Excessive Efficiency.

-> JavaScript In every single place.

-> Simple to Modify and Preserve.

-> Simple to keep up.

15) How one can set up npm in nodejs?

whereas putting in nodejs in your laptop npm comes with it. so we don’t need to obtain one other setup and set up it.
You’ll be able to test the npm model by typing npm -v on terminal/Command Immediate.

16) What’s MORGAN in node js

effectively there are various HTTP request logger center ware for Node.js like

-> Node-Loggly

-> Bunyan

-> Winston

however the preferred one is Morgan

Morgan is a utility software which helps us to console or log HTTP request from request-response cycle.

17) How one can set up node js

Step 1: go to this web site 

→ https://nodejs.org/en/obtain/

Step 2: After that, you will note a number of working system choices select no matter working system you’re operating. If you’re operating home windows then click on on home windows Installer or in case you are operating macOS then click on on macOS Installer or in case you are operating Linux then click on on supply code.
Step 3: for checking nodejs is efficiently set up or not you possibly can go to cmd line or terminal in mac, then kind node -v for checking node model.

18)  How one can set up node js in home windows

step 1: go to https://nodejs.org/en/.

Step 2: now obtain newest LTS model which stands for Lengthy Time period Help.

Step 3: after finishing  obtain double click on on installer and set up the software program by accepting all phrases and situation.

Step 4: After accepting all phrases and circumstances click on on set up, set up will take hardly 2-5 min relying in your system configuration.

Step 5: for checking nodejs is efficiently set up or not you possibly can go to cmd line or terminal in mac, then kind node -v for checking node model.

19) How one can set up categorical in node js?

     Specific is among the hottest net framework for node. 

Step 1: earlier than putting in categorical we’ve got to initialize folder with command npm init.

Step 2: press enter for filling default worth in it.

Step 3: now kind npm i categorical for putting in categorical.

Step 4: for utilizing npm in your mission rgb(247, 247, 247)

20) How one can run node js server?

Step 1: for operating nodejs server we require categorical and port on which our net server will run is that this it’s port 8001.

Step 2: setting categorical to get (get request) from our server which your native host.

Step 3: with the assistance of app.pay attention we’re itemizing on port 8001.

Step 4: now kind node and title of file you need ot run in my case it’s index.js so kind 

  > node index.js

step 5: As we are able to see we’re efficiently capable of render your web site.

21) How one can run file from node command immediate??

open your command immediate in case you are in home windows or terminal in case you are in mac/Linux after which kind node -v.

22) What’s categorical in node Js??

Specific is among the hottest net framework for node.  It have 16,631,385 Weekly downloads on npm with a really small dimension unpacked dimension is about 209KB.

Specific assist us to construct your web site sooner strong and simple to keep up code.

23) how one can open node js command immediate

earlier than opening nodejs command immediate set up nodejs and NPM.

Step 1: set up nodejs from https://nodejs.org/en/ .

Step 2: run the installer and go away each factor to default and settle for time period and situation.

Step 3:  write code on js file.

step 4: run JS file through the use of command node and title of file.

24) How one can render HTML utilizing node js?

Step 1: require categorical module and outline port no. In my case its 8001.

Step 2: set a get request on ‘/’ route for sending a get request we use res.ship technique to ship content material to web site.

Step 3: in my case I wish to despatched a HTML tag and render that tag, so we use

MyGreatLearnig

  HTML tag and put within the res.ship() technique.

Step 4: now we’ve got to pay attention the request(req) and response(res) to the request on port. 


step 5:
As we are able to see we’re efficiently capable of render your web site.

25) Your favorite Nodejs framework and why?

  1. Mongoose
  • Mongoose offers a straight-forward and schema-based resolution to mannequin and handle your database and designed to work in an asynchronous surroundings and helps each guarantees and callbacks which good appropriate with NodeJS.
  • It has 1,226,217 weekly downloads.
  1. Specific.js
  • Expressjs is an internet body Work construct on prime of nodejs. 
  • Expressjs deal with completely different HTTP requests (req) akin to fundamental routing, middleware, template engine and static information serving.
  • It has Weekly Downloads of 16,623,215.
  1. Pug
  • PUG is template engine which in-built prime of JS that’s utilized within the Node. js scheme. It’s a library that render HTML our bodies.
  • It has Weekly Downloads 1,163,220
  1. Chalk
  • A easy string styling performed on terminal. It assist us builders to distinguish between completely different kind of output on terminal.
  • It has Weekly Downloads 84,131,453.
  1. Morgan
  • because the title says  it generate huge quantity of faux information for testing your software.
  • It has Weekly Downloads 2,783,928.
  1. faker.js
  • one essentially the most helpful dev utility for logging HTTP request on the console. It has Weekly Downloads of two,095,542.

26) Can your write a easy instance of an Asynchronous perform in nodejs?

A standard perform might be written as an async perform by including a key phrase async on entrance of the perform.

27) What’s the LTS releases of Node.js?

An LTS stands for (Lengthy Time period Help) are supported for at the least 18 months and receives all bug repair, stability, safety patch efficiency. Additionally, they’re backwards appropriate.

The place as non LTS  have some minor bug which may break your software.

28) What’s Callbacks?

 A perform is handed into one other perform as an argument is named callback perform.

29) What’s the distinction between Asynchronous and Non-blocking

The design of asynchronous explains that the message despatched received’t present the reply on fast foundation a bit like we are likely to ship the mail nonetheless don’t get the reply on an immediate foundation. It doesn’t have any dependency or order. thus up the system efficiency and efficiency. The server shops the info and as soon as the motion is accomplished it’ll be notified.

Non-blocking now responses with regardless of info obtainable. Furthermore, it doesn’t block any execution and retains on operating as per the requests. If an answer couldn’t be retrieved then in these circumstances API returns now with a blunder. Non-blocking is often used with I/O(enter/output). Node.js is itself supported by a non-blocking I/O mannequin. There are unit few ways in which of communication {that a} non-blocking I/O has accomplished. The asking operation is to be identified as soon as the operation is accomplished. Non-blocking resolution makes use of the help of JavaScript that gives an asking.

30) What does the runtime surroundings imply in Node.js?

The Node.js runtime is that the code stack answerable for operating your code on the respective platform and operating your service on the server.

31) What are Guarantees in Node.js?

it permits to affiliate handlers to AN asynchronous motion’s final success worth or failure purpose. This lets asynchronous methods come again costs like synchronous strategies: slightly than the last word worth, the asynchronous method returns a promise for the value at some goal inside the future.

32) What’s a stub?

Stubbing and verification for node.js exams. lets you validate and override habits of nested objects of code like strategies, require() and npm modules or possibly cases of classes. This library is galvanized on node-gently, MockJS and mock-require.

Function:

  • Produces easy, lightweight Objects able to extending down their tree
  • Stubs give canned solutions to carry out calls created all through test circumstances. Additionally, you’ll assert on with what these stubs have been referred to a
  • Successfully extendable straight forwardly or by way of an ExtensionManager.

33)  What’s REPL?

REPL (READ, EVAL, PRINT, LOOP) may very well be a system surroundings nearly like Shell in (Unix/Linux) and cmd/terminal. NodeJS comes with the REPL setting as soon as it’s put in. The system interacts with the consumer by way of outputs of instructions/expressions used. it’s useful in writing and debugging the codes.

34) How one can join mongodb with node js?

Step 1: require mongoose package deal for monodb.

Step 2: kind password on the place of and Retailer it on const DB.

Step 3: move an object technique on the place useNewUrlParser set to true.

Step 4: move an object technique on the place useCreateIndex set to true,

Step 5: move an object technique on the place useFindAndModify set to true,

Step 6: move an object technique on the place useUnifiedTopology set to true,

{

    useNewUrlParser: true,

    useCreateIndex: true,

    useFindAndModify: false,

    useUnifiedTopology: true,

  }

35) how one can set up node js in Linux?

Step 1: open your terminal.

Step 2: kind sudo apt set up nodejs in your terminal and hit enter.

Step 3: for putting in npm.

Step 4: kind sudo apt set up npm in your terminal and hit enter.

36) What are the forms of API capabilities in Node.js?

Their are 2 forms of API capabilities accessible in Node.js:-

  • non-blocking capabilities, Asynchronous.
  • blocking capabilities, Synchronous,

37) Can I run nodejs on home windows?

Sure – it does. 

You’ll be able to Obtain the nodejs installer in your respective Working System 

from 👉 https://nodejs.org/obtain/ 

38) how will you use exterior libraries in node.js?

Suppose we wish to use a library known as categorical :-

  1. Set up that library utilizing npm command npm set up categorical.
  2. After putting in library require it utilizing const categorical = require(“categorical”);
  3. The library is able to use in your mission.

39) Does the fs module offers each syncs in addition to async strategies ??

sure  fs module offers each sync in addition to async strategies.

40) What’s __dirname variable?

__dirname variable print the working listing.

41) Are you able to clarify the blocking code?

If the appliance has acquired to watch for some I/O operation in order to finish its execution any longer then the code liable for ready is regarded as blocking code.

42) What’s the Occasion loop in Node.js work? And How does it work?

By default, JavaScript is a single-threaded language for fixing this behaviour JavaScript distributing the duty to the respective system kernel, as a result of a lot of the fashionable kernel help multi-threading these days which suggests the kernel can run the duty within the background with out blocking the present execution stack this gap phenomena known as occasion loop as a result of nodejs is constructed on the highest of nodejs, nodejs can also be a single-threaded however with the assistance of kernel Node.js to carry out non-blocking I/O operations.

43) What are the important thing options of Node.js?

Main key options of NodeJS are:

Asynchronous event-driven IO helps concurrent request dealing with –> All APIs of NodeJS is asynchronous in nature. This function means if a Node receives asking for some Enter/Output job, it’ll execute that function inside the background and proceed with the method of different requests. so it’ll not look ahead to the response from the earlier requests.

Code execution –>Code execution is far sooner on Node.js, Nodejs makes use of the V8 engine which is open-source and maintained by google additionally powers Google Chrome net browser.

Single-Threaded however Extremely scalable –> Node.js makes use of a single thread mannequin for the occasion course of. The response from these occasions might or may not attain the server directly. Nonetheless, this doesn’t block completely different operations. subsequently creating Node.js extraordinarily scalable. The response from these events was servers produce restricted threads to deal with requests whereas Node.js creates one thread that has service to considerable bigger numbers of such requests.

Node.js library makes use of JavaScript – That is one other vital a part of Node.js from the engineer’s perspective. Most designers are as of now educated in JavaScript. Subsequently, enchancment in Node.js will get less complicated for an engineer who is aware of JavaScript.

44) Which IDEs or code Editor you like for Node.js growth? And why

Private I take advantage of visible studio code as a result of it’s free open-source and builders of visible studio code all the time giving patches for safety and efficiency replace as effectively.
Speaking about IDEs I usually desire net storm which is developed by Jet Brains.
And particularly targeted on net growth so it has all the mandatory instruments for constructing a web site or an internet software.

45) Give a real-world instance of the working mechanism of NodeJS?

I’m taking an instance of a deliveryman

Often, the deliveryman goes to each and each home to ship the packet. Node.js works inside the identical technique and processes one request at a time. the matter arises as soon as anyone’s residence will not be open. The supply man can’t cease at one home and wait till it will get displayed. What he can do subsequent, is to resolution the proprietor and lift him to the choice as soon as the house is open. In the meantime, he’s attending to different locations for supply. Node.js works inside the identical technique. It doesn’t look ahead to the method of the request to finish (the home is open). As a substitute, it attaches a recall operation (name from the proprietor of the home) to that. Every time the method of the a call for participation completes (the house is open), a taking place will get often called that triggers the related recall operates to ship the response.

46) Is Node.js fully based mostly on a single-thread or not?

Sure it true that nodejs relies on single-thread.

47) What’s package deal.json?

package deal.json is one a very powerful file for engaged on nodejs. It’s plain JSON file the place mission frequent info and meta information saves. 

Which look one thing like this

{
  "title": "mission Title",
  "model": "1.0.0",
  "description": "TODO",
  "predominant": "index.js",
  "scripts": {
    "begin": "node index.js"
  },
  "writer": "title of writer",
  "license": "ISC",
  "dependencies": {
    "categorical": "^4.17.1"
  }
}

48) How one can get a distant Tackle in node js?

Through the use of req perform we are able to get consumer’s IP handle in node js.

Code ->  req.connection.remoteAddress 

49) What’s DOM?

Dom stands for doc object mannequin.

50) Is there’s different to question Selector?

sure it’s  doc.getElementBy 

1)  relational -> These information-based are categorized by a group of tables wherever information get work right into a per-defined class. The desk consists of rows affiliate levels columns wherever the column has an entry for info for a particular class and rows incorporates occasion for that info outlined consistent with the category. The Structured search language (SQL) is that the commonplace consumer and laptop program interface for an digital info service.

Instance  MySQL, PostgreSQL, Oracle Database

2) No SQL database (non relational Database) -> These are used for large units of distributed info. Some huge info efficiency issues are successfully dealt with by relative databases, such quiet issues are merely managed by No SQL databases. They’re have been economical in analyzing giant-size unstructured info which shall be held on a number of digital servers of the cloud.

Instance MongoDB

3) Graph -> The graph may very well be an assortment of nodes and edges wherever each node is employed to symbolize an entity and each edge describes the connection between entities. Graph-oriented information, or graph information, may very well be a type of No SQL information that makes use of graph concept to retailer, map, and query relationships.

ReactJS -> Created by Fb, the React framework may be very standard these days and it wont to develop and function the dynamic interface of the web pages with excessive incoming visitors. It makes the utilization of a digital DOM, and therefore, the blending of an equal with any software is moreover straightforward.

Meteor -> Meteor’s software house (aka Meteor.js or MeteorJS) serves the title itself because it’s assorted as a result of it covers nearly the numerous parts of the code growth. The makes use of of this framework embrace important areas like back-end growth, administration of the data, enterprise logic, and rendering of the front-end.

These Node.js interview questions would enable you perceive what sort of questions might are available in an interview, undergo these Node.js interview questions, and crack your subsequent interview in a single go.

All The Finest in your Interview

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