Node Js Interview Questions And Answers

Node Js Interview Questions list for experienced

  1. What is the purpose of Node.js module.exports and how do you use it?
  2. How do you extract POST data in node.js?
  3. How to decide when to use Node.js?
  4. how to write files in Node.js?
  5. How to debug Node.js applications?
  6. How to get GET (query string) variables in Express on node.js?
  7. What is node.js?
  8. How node.js works?
  9. What do you mean by the term I/O ?
  10. What does event-driven programming mean?
  11. Where can we use node.js?
  12. What is the advantage of using node.js?
  13. What is 'Callback' in node.js?
  14. What does it mean "non-blocking" in node.js?
  15. What are the pros and cons of Node.js?
  16. How to parse JSON using Node.js?
  17. Can we use jQuery with Node.js?
  18. How to get started with Node.js?
  19. Explain Node.js Architecture?
  20. Is Node.js on multi-core machines?
  21. Are you sure node.js execute system command synchronously?
  22. Tell me how to use underscore.js as a template engine?
  23. Do you know what mean stack means?
  24. What is the difference between Node.js vs Ajax?
  25. Mention the steps by which you can async in Node.js?
  26. What are the two arguments that async.queue takes?
  27. Why node.js is quickly gaining attention from JAVA programmers?
  28. Using the event loop what are the tasks that should be done asynchronously?
  29. Explain the steps how "Control Flow" controls the functions calls?
  30. Why Node.js is single threaded?
  31. What are the two types of API functions in Node.js ?
  32. What tool and IDE is used for Node.js?
  33. How to handle the \"Unhandled exceptions\" in Node.js?
  34. Is Nodejs really Single-Threaded
  35. Can you explain what is Globals in Nodejs
  36. What is the Use of underscore in Nodejs?
  37. Can you create Http Server in Nodejs, explain with code
  38. Can you explain the difference between readFile vs createReadStream in Nodejs
  39. Is node js a programming language?
  40. What is the use of Nodejs?
  41. Is node JS frontend or backend?
  42. What is the framework that is used majorly in Node.js today?
  43. What are the security implementations that are present in Node.js?
  44. What is the meaning of a test pyramid?
  45. What is Libuv?
  46. What is the use of middleware in Node.js?
  47. What are global objects in Node.js?
  48. How is a test pyramid implemented using the HTML API in Node.js?
  49. Why is a buffer class used in Node.js?
  50. Why is ExpressJS used?
  51. What is the use of the connect module in Node.js?
  52. What are streams in Node.js?
  53. What are the types of streams available in Node.js?
  54. What is the use of REPL in Node.js?
  55. What is meant by tracing in Node.js?
  56. Where is package.json used in Node.js?
  57. What is the difference between readFile and createReadStream in Node.js?
  58. What is a passport in Node.js?
  59. How does the DNS lookup function work in Node.js?
  60. What is the difference between setImmediate() and setTimeout()?
  61. Why do you think you are the right fit for this Node.js role?
  62. Do you have any past Node.js work experience?
  63. Do you have any experience working in the same industry like ours?
  64. Do you have any certification to boost your candidature for this Node.js role?
  65. What is express.js.
  66. How many types of API Functions available in Node.js ?
  67. How can we managed the packages in our Node.js Projects?
  68. What is Callback Hell in Node.js?
  69. Which types of applications is Node.js most frequently used?
  70. How to I get the GET (query string) variables in Express.js on Node.js?
  71. How to install express.js. in mern stack development.
  72. How to install node.js?
  73. Node JS with Express API returning null instead undefined in array items?
  74. How do I pass command line arguments to the Node.js program?
  75. What's the difference between tilde(~) and caret(^) in package.json?
  76. Remove all child elements of a DOM node in JavaScript?
  77. What is the most efficient way to deep clone an object in the JavaScript?
  78. How to undo "git commit --amend" done instead of "git commit"?
  79. What does the "yield" keyword do?
  80. Execute a command line binary with Node.js?
  81. What are the options for storing hierarchical data in a relational database?
  82. How to store Node.js deployment settings/configuration files?
  83. List all in built module of node JS in details

Node Js interview questions and answers on advance and basic Node Js with example so this page for both freshers and experienced condidate. Fill the form below we will send the all interview questions on Node Js also add your Questions if any you have to ask and for apply in Node Js Tutorials and Training course just send a mail on info@pcds.co.in in detail about your self.

Top Node Js interview questions and answers for freshers and experienced

What is Node Js ?

Answer : Node.js is an event-based, non-blocking, asynchronous I/O framework that uses Google\'s V8 JavaScript engine

Questions : 1 :: What is the purpose of Node.js module.exports and how do you use it?

module.exports is the object that's actually returned as the result of a require call.The exports variable is initially set to that same object (i.e. it's a shorthand "alias"), so in the module...View answers

Questions : 2 :: How do you extract POST data in node.js?

HTML: <form method="post" action="/"> <input type="text" name="user[name]"> <input type="text" name="user[email]"> <input type="submit"...View answers

Questions : 3 :: How to decide when to use Node.js?


Node.js consider to be used in specific scenario. If your app does not fit into that scenario you should not consider it for your app development.When to use Node.JS If your server side code...View answers

Questions : 4 :: how to write files in Node.js?

Currently there are 3 ways to write a file: fs.write(fd, buffer, offset, length, position, [callback]) You need to wait for the callback to ensure that the buffer is written to disk. It's not...View answers

Questions : 5 :: How to debug Node.js applications?

There are a few tools and ways out there: => Joyent's Guide Joyent now maintains their own debugging guide. It's worth a look. =>Interactive Stack Traces with traceGL =>Profiling with...View answers

Questions : 6 :: How to get GET (query string) variables in Express on node.js?


var url = require('url');var url_parts = url.parse(request.url, true);var query = url_parts.query;

Questions : 7 :: What is node.js?

Node.js is a Server side scripting which is used to build scalable programs. Its multiple advantages over other server side languages, the prominent being non-blocking...View answers

Questions : 8 :: How node.js works?

Node.js works on a v8 environment, it is a virtual machine that utilizes JavaScript as its scripting language and achieves high output via non-blocking I/O and single threaded event...View answers

Questions : 9 :: What do you mean by the term I/O ?


i/O is the shorthand for input and output, and it will access anything outside of your application. It will be loaded into the machine memory to run the program, once the application is...View answers

Questions : 10 :: What does event-driven programming mean?

In computer programming, event driven programming is a programming paradigm in which the flow of the program is determined by events like messages from other programs or threads. It is an...View answers

Questions : 11 :: Where can we use node.js?

Node.js can be used for the following purposes a)      Web applications ( especially real-time web apps ) b)      Network...View answers

Questions : 12 :: What is the advantage of using node.js?

a)      It provides an easy way to build scalable network programs b)      Generally fast c)       Great...View answers

Questions : 13 :: What is 'Callback' in node.js?

Callback function is used in node.js to deal with multiple requests made to the server. Like if you have a large file which is going to take a long time for a server to read and if you...View answers

Questions : 14 :: What does it mean "non-blocking" in node.js?

In node.js “non-blocking” means that its IO is non-blocking.  Node uses “libuv” to handle its IO in a platform-agnostic way. On windows, it uses completion...View answers

Questions : 15 :: What are the pros and cons of Node.js?

Pros: a)      If your application does not have any CPU intensive computation, you can build it in Javascript top to bottom, even down to the database level if you...View answers

Questions : 16 :: How to parse JSON using Node.js?

simply use JSON object: JSON.parse(str);JSON.parse. node.js is built on V8, which provides the global object JSON[docs]. The definition of the JSON object is part of the ECMAScript 5...View answers

Questions : 17 :: Can we use jQuery with Node.js?

No. It's going to be quite a big effort to port a browser environment to node.Another approach, that I'm currently investigating for unit testing, is to create "Mock" version of jQuery...View answers

Questions : 18 :: How to get started with Node.js?

First, learn the core concepts of Node.js:You'll want to understand the asynchronous coding style that Node encourages.Async != concurrent. Understand Node's event loop!Node uses...View answers

Questions : 19 :: Explain Node.js Architecture?

There are four building blocks that constitute Node.js. First, Node.js encapsulates libuv to handle asynchronous events and Google’s V8 to provide a run-time for JavaScript. Libuv is...View answers

Questions : 20 :: Is Node.js on multi-core machines?

Yes, Node.js is one-thread-per-process. This is a very deliberate design decision and eliminates the need to deal with locking semantics. If you don't agree with this, you probably don't...View answers

Questions : 21 :: Are you sure node.js execute system command synchronously?

There's an excellent module for flow control in node.js called asyncblock. If wrapping the code in a function is OK for your case, the following sample may be considered:var asyncblock =...View answers

Questions : 22 :: Tell me how to use underscore.js as a template engine?

Everything you need to know about underscore template is here. Only 3 things to keep in mind:<% %> - to execute some code<%= %> - to print some value in template<%- %> - to...View answers

Questions : 23 :: Do you know what mean stack means?

MEAN stack stands for MongoDB-Express-AngularJS-NodeJS. First of all, MEAN is JS-only environment. Express is one of the most popular web app frameworks for NodeJS. Node.JS development...View answers

Questions : 24 :: What is the difference between Node.js vs Ajax?

The difference between Node.js and Ajax is that, Ajax (short for Asynchronous Javascript and XML) is a client side technology, often used for updating the contents of the page without...View answers

Questions : 25 :: Mention the steps by which you can async in Node.js?

By following steps you can async Node.js a)      First class functions b)      Function...View answers

Questions : 26 :: What are the two arguments that async.queue takes?

The two arguments that async.queue takes a)      Task function b)      Concurrency...View answers

Questions : 27 :: Why node.js is quickly gaining attention from JAVA programmers?

Node.js is quickly gaining attention as it is a loop based server for JavaScript. Node.js gives user the ability to write the JavaScript on the server, which has access to things like HTTP...View answers

Questions : 28 :: Using the event loop what are the tasks that should be done asynchronously?

a)      I/O operations b)      Heavy computation c)       Anything requiring...View answers

Questions : 29 :: Explain the steps how "Control Flow" controls the functions calls?

a)      Control the order of execution b)      Collect data c)       Limit...View answers

Questions : 30 :: Why Node.js is single threaded?

For async processing, Node.js was created explicitly as an experiment. It is believed that more performance and scalability can be achieved by doing async processing on a single thread...View answers

Questions : 31 :: What are the two types of API functions in Node.js ?

The two types of API functions in Node.js are a)      Asynchronous, non-blocking functions b)      Synchronous, blocking...View answers

Questions : 32 :: What tool and IDE is used for Node.js?

=>Nodeclipse Enide Studio=>JetBrains WebStorm=>JetBrains IntelliJ IDEA=>Microsoft Visual Studio with TypeScript=>NoFlo – flow-based...View answers

Questions : 33 :: How to handle the "Unhandled exceptions" in Node.js?

It can be caught at the "Process level" by attaching a handler for uncaughtException event.Example: process.on('uncaughtException', function(err) {...View answers

Questions : 34 :: Is Nodejs really Single-Threaded

Node.js operates on single-thread, but using non-blocking I/O calls allows it to support many concurrent connections. That means node doen't process the...View answers

Questions : 35 :: Can you explain what is Globals in Nodejs

Global, Process and Buffer are combinedly termed as Globals.Global : Its a global namespace objectProcess : Its also a global object but it provides essential...View answers

Questions : 36 :: What is the Use of underscore in Nodejs?

To access the last expression, we have to use the (_) underscore/underline...View answers

Questions : 37 :: Can you create Http Server in Nodejs, explain with code

Yes, we can create Http Server in Nodejs. We can use http-server command to do so.Code :var http = require('http');var requestListener = function (request,...View answers

Questions : 38 :: Can you explain the difference between readFile vs createReadStream in Nodejs

readFile - It will read the file completely into memory before making it available to the User.createReadStream - It will read the file in chunks of the size...View answers

Questions : 39 :: Is node js a programming language?

 As Node. js is not the traditional programming language, but rather a runtime environment, it is easy to learn for both front and back-end developers.  JavaScript is a language....View answers

Questions : 40 :: What is the use of Nodejs?

  Node. js is a stage based on Chrome's JavaScript runtime for effectively constructing quick and versatile system applications. Hub. js utilizes an occasion driven, non-blocking I/O model that...View answers

Questions : 41 :: Is node JS frontend or backend?

Node. js is a runtime environment, which let users choose how to use, whether frontend or backend, and one common language can be used as backend and front end. This environment is entirely based on...View answers

Questions : 42 :: What is the framework that is used majorly in Node.js today?

Node.js has multiple frameworks, namely: Hapi.js Express.js Sails.js Meteor.js Derby.js Adonis.js Among these, the most used framework is Express.js for its ability to provide good...View answers

Questions : 43 :: What are the security implementations that are present in Node.js?

Following are the important implementations for security: Error handling protocols Authentication...View answers

Questions : 44 :: What is the meaning of a test pyramid?

A test pyramid is a methodology that is used to denote the number of test cases executed in unit testing, integration testing, and combined testing (in that order). This is maintained to ensure that...View answers

Questions : 45 :: What is Libuv?

Libuv is a widely used library present in Node.js. It is used to complement the asynchronous I/O functionality of Node.js. It was developed in-house and used alongside systems such as Luvit, Julia,...View answers

Questions : 46 :: What is the use of middleware in Node.js?

A middleware is a simple function that has the ability to handle incoming requests and outbound response objects. Middleware is used primarily for the following tasks: Execution of code (of any...View answers

Questions : 47 :: What are global objects in Node.js?

Global objects are objects with a scope that is accessible across all of the modules of the Node.js application. There will not be any need to include the objects in every module. One of the objects...View answers

Questions : 48 :: How is a test pyramid implemented using the HTML API in Node.js?

Test pyramids are implemented by defining the HTML API. This is done using the following: A higher number of unit test cases A smaller number of integration test methods A fewer number of HTTP...View answers

Questions : 49 :: Why is a buffer class used in Node.js?

A buffer class is primarily used as a way to store data in Node.js. This can be considered as a similar implementation of arrays or lists. Here, the class refers to a raw memory location that is not...View answers

Questions : 50 :: Why is ExpressJS used?

ExpressJS is a widely used framework built using Node.js. Express.js uses a management point that controls the flow of data between servers and server-side applications. Being lightweight and...View answers

Questions : 51 :: What is the use of the connect module in Node.js?

The connect module in Node.js is used to provide communication between Node.js and the HTTP module. This also provides easy integration with Express.js, using the middleware...View answers

Questions : 52 :: What are streams in Node.js?

Streams are a set of data entities in Node.js. These can be considered similar to the working of strings and array objects. Streams are used for continuous read/write operations across a channel....View answers

Questions : 53 :: What are the types of streams available in Node.js?

Node.js supports a variety of streams, namely: Duplex (both read and write) Readable streams Writable streams Transform (duplex for modifying...View answers

Questions : 54 :: What is the use of REPL in Node.js?

REPL stands for Read-Eval-Print-Loop. It provides users with a virtual environment to test JavaScript code in Node.js. To launch REPL, a simple command called ‘node’ is used. After this,...View answers

Questions : 55 :: What is meant by tracing in Node.js?

Tracing is a methodology used to collect all of the tracing information that gets generated by V8, the node core, and the userspace code. All of these are dumped into a log file and are very useful...View answers

Questions : 56 :: Where is package.json used in Node.js?

The ‘package.json’ file is a file that contains the metadata about all items in a project. It can also be used as a project identifier and deployed as a means to handle all of the project...View answers

Questions : 57 :: What is the difference between readFile and createReadStream in Node.js?

readFile: This is used to read all of the contents of a given file in an asynchronous manner. All of the content will be read into the memory before users can access it. create...View answers

Questions : 58 :: What is a passport in Node.js?

Passport is a widely used middleware present in Node.js. It is primarily used for authentication, and it can easily fit into any Express.js-based web application. With every application created, it...View answers

Questions : 59 :: How does the DNS lookup function work in Node.js?

The DNS lookup method uses a web address for its parameter and returns the IPv4 or IPv6 record, correspondingly. There are other parameters such as the options that are used to set the input as an...View answers

Questions : 60 :: What is the difference between setImmediate() and setTimeout()?

The setImmediate() function is meant to execute a single script once the current event loop is complete. The setTimeout() function is used to hold a script and schedule it to be run after a certain...View answers

Questions : 61 :: Why do you think you are the right fit for this Node.js role?

Here, the interviewer wants to know your understanding of the job role and the company architecture and your knowledge on the topic. While answering this question, it would add immensely if you knew...View answers

Questions : 62 :: Do you have any past Node.js work experience?

This question is common among Node.js interviews. Make sure to answer it to the best of your abilities, and do not bloat but give your honest experiences and explain how you’ve used Node.js...View answers

Questions : 63 :: Do you have any experience working in the same industry like ours?

With this question, the interviewer is trying to assess if you’ve had any previous work experience or internship experience where you dealt with similar working environments or technologies....View answers

Questions : 64 :: Do you have any certification to boost your candidature for this Node.js role?

t is always advantageous to have a certification in the technology that you’re applying for. This gives the interviewer the impression that you have worked on the technology and that you are...View answers

Questions : 65 :: What is express.js.

Express.js is back-end web application framework for node.js. It is the open-source software under mit license. The original author, TJ Holowaychuk, described as a Sinatra-inspired...View answers

Questions : 66 :: How many types of API Functions available in Node.js ?

  There are two types of API functions available in Node.js :1)Asynchronous, non blocking functions .2) Synchronous, blocking functions . Nods.js is an interpreter and run-time enviroment for...View answers

Questions : 67 :: How can we managed the packages in our Node.js Projects?

It can be managed by using several packages installer and their configuration files. Maximum usages is NPM and YARN.Both of them provides almost all the libraries of Javascripts With extended...View answers

Questions : 68 :: What is Callback Hell in Node.js?

Callback hell is a phenomenon it creates a lot of problems for a JavaScript developer when tries to execute multiple asynchronous operations one after the other. It is called an asynchronous function...View answers

Questions : 69 :: Which types of applications is Node.js most frequently used?

Node.js is most frequently and widely used in the following applications:1) Internet of Things2) Real-time collaboration tools3) Real-time chats4) Complex SPAs (Single-Page Applications)5) Streaming...View answers

Questions : 70 :: How to I get the GET (query string) variables in Express.js on Node.js?

First equation to get the variable string (value.query.id) sovar express = require('express');var app = express(); app.get('/', function(req, res){ res.send('id: ' +...View answers

Questions : 71 :: How to install express.js. in mern stack development.

 create cluster  If we want to install express.js on windows with mongoDB. I gonna go to twerminal and type (npm install express cors dotenv) after some express.js installed in my system we...View answers

Questions : 72 :: How to install node.js?

There have various step to install node.js on windows machine are:-1. Download Node.js Installer for Windows Go to the site https://nodejs.org/en/download/ and download the necessary binary files....View answers

Questions : 73 :: Node JS with Express API returning null instead undefined in array items?

The res.send return a JSON, and undefined is not a valid JSON value, even though it is valid in javascript.

Questions : 74 :: How do I pass command line arguments to the Node.js program?

process.argv is an array containing the command line arguments. The first element will be 'node', the second element will be the name of the JavaScript file. The next elements will be any additional...View answers

Questions : 75 :: What's the difference between tilde(~) and caret(^) in package.json?

There have two points to explain the tilde and caret are:- 1. ~version “Approximately equivalent to version”, will update you to all future patch versions, without incrementing the minor...View answers

Questions : 76 :: Remove all child elements of a DOM node in JavaScript?

An earlier edit to this answer used firstChild, but this is updated to use lastChild as in computer-science, in general, it's significantly faster to remove the last element of a collection than it...View answers

Questions : 77 :: What is the most efficient way to deep clone an object in the JavaScript?

 The name of deep cloning is Native deep cloning There's now a JS standard called "structured cloning", that works experimentally in Node 11 and later, will land in browsers, and which has...View answers

Questions : 78 :: How to undo "git commit --amend" done instead of "git commit"?

If you have pushed the commit to remote and then erroneously amended changes to that commit this will fix your problem. Issue a git log to find the SHA before the commit. (this assumes remote is...View answers

Questions : 79 :: What does the "yield" keyword do?

Below is the example of yield codes are:- >>> def create_generator():... mylist = range(3)... for i in mylist:... yield i*i...>>> mygenerator = create_generator() # create a...View answers

Questions : 80 :: Execute a command line binary with Node.js?

For even newer version of Node.js (v13.3.6), the events and calls are similar or identical to older versions, but it's encouraged to use the standard newer language features. Examples: For buffered,...View answers

Questions : 81 :: What are the options for storing hierarchical data in a relational database?

My favorite answer is as what the first sentence in this thread suggested. Use an Adjacency List to maintain the hierarchy and use Nested Sets to query the hierarchy. The problem up until now has...View answers

Questions : 82 :: How to store Node.js deployment settings/configuration files?

I use a package.json for my packages and a config.js for my configuration, which looks like: var config = {}; config.twitter = {};config.redis = {};config.web = {}; config.default_stuff =...View answers

Questions : 83 :: List all in built module of node JS in details

Node.js has a Multiple built-in modules below which we can use without any installation just need to import.   Module assert Provides a set of assertion tests buffer To handle binary...View answers
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