The number of Node JS jobs is on the rise, and this quotes directly to putting yourself up against the increased competition. This calls for the most in-depth preparation you can get. This top Node JS interview questions blog is carefully curated to give you answers to some of the most asked questions in a Node JS interview. Upon using the guide carefully, you can get the competitive edge that is required to ace your interview.
Preparing for a Node.js interview can involve several steps, and here are a few tips to help you prepare:
- Know the basics of Node Js: You should have a solid understanding of the fundamental concepts of Node.js, including asynchronous programming, event-driven architecture, modules, and callbacks.
- Understand JavaScript: Since Node JS is built on top of JavaScript, it's essential to have a strong grasp of JavaScript concepts and syntax, such as functions, data types, and object-oriented programming.
- Familiarize yourself with popular Node JS libraries and frameworks: You should know about the most popular Node JS libraries and frameworks like Express, Koa, and Nest.js.
- Practice coding: Spend some time practicing coding in Node JS, by working on small projects or taking online coding challenges. This will help you get comfortable with the language and develop your problem-solving skills.
- Prepare for behavioral questions: Be ready to answer behavioral questions, as many interviewers will want to learn more about your experience, work style, and problem-solving approach.
- Research the company and the position: Spend some time learning about the company you're interviewing with and the role you're applying for. This will help you tailor your responses to the interviewer's questions and demonstrate your interest in the position.
- Be prepared for technical questions: The interviewer may ask you technical questions related to Node Js, including the architecture of a Node JS app, creating and using middleware, error handling, and debugging techniques.
Q1) What is node.js?
Node.js is a server side scripting that can be used to create advanced programs. Its many advantages
Other server side languages, mainly non-blocking I / O.
Q2) How does node.js work?
Node.js runs in a V8 environment, a virtual machine that uses JavaScript as scripting
Language and non-blocking I / O and single threaded event reaches high output through the loop.
Q3) What does the term I / O mean?
I / O is the shorthand for input and output, which will access anything outside of your application. This will happen
Once the application is started, the machine will be loaded to run the program.
Also Read: C Programming: A Step-by-Step Complete Guide
Q4) What does event-driven programming mean?
In computer programming, event driven programming is a programming paradigm with flow
The program is determined by events such as messages from other projects or texts. it is a
The application structure technique is split into two sections 1) Event selection 2) Event handling
Q5) Where can we use node.js?
Node.js can be used for the following purposes
- Web applications (especially real-time web applications)
- network applications
- Distributed systems
- general purpose applications
Q6) What is the benefit of using node.js?
- This is the easiest way to create measurable network schemes
- Generally fast
- better integration
- everything that is not asynchronous
- There are almost no blocks
Q7) Types of API functions in Node.js?
Node.js has two types of API functions
- Asynchronous, non-preventive operations
- synchronize and prevent operations
Q8) What is the control flow function?
Many asynchronous function is known as a common piece of code running between calls
Control flow functionality.
Q9) Explain how “Control Flow” controls functional calls.
- Control the execution order
- Collect data
- integration limit
- Call the next step in the program
Q10) Why is Node.js single thread?
For the Async process, Node.js was created explicitly as a test. It is very much believed
Performance and scaling can be achieved through a single oscillation process
Typical web loads than regular thread-based implementation.
Also Read: AngularJs Important Interview Questions and Answers
11. What is an error-first callback in Node.js?
Error-first callbacks in Node.js are used to pass errors and data. The very first parameter you need to pass to these functions has to be an error object while the other parameters represent the associated data. Thus you can pass the error object for checking if anything is wrong and handle it. In case there is no issue, you can just go ahead and with the subsequent arguments.
1 2 3 4 5 6 7 | var myPost = new Post({title: 'edureka'});myPost.save(function(err,myInstance){if(err){//handle error and return}//go ahead with `myInstance`}); |
12. Explain the purpose of module.exports?
A module in Node.js is used to encapsulate all the related codes into a single unit of code which can be interpreted by shifting all related functions into a single file. For example, suppose you have a file called greet.js that contains the two functions as shown below:
1 2 3 4 5 6 7 | module.exports = {greetInHindi: function(){return "NAMASTE";},greetInKorean: function(){return "ANNYEONGHASEYO";}}; |
As you can see module.exports provide two functions which can be imported in another file using below code:
1 2 3 | var eduGreets = require ("./greet.js");eduGreets.greetInHindi() //NAMASTEeduGreets.greetInKorean() //ANNYEONGHASEYO |
13. What do you understand by Reactor Pattern in Node.js?
Reactor Pattern in Node.js is basically a concept of non-blocking I/O operations. This pattern provides a handler that is associated with each I/O operation and as soon as an I/O request is generated, it is then submitted to a demultiplexer. This demultiplexer is a notification interface which is capable of handling concurrency in non-blocking I/O mode. It also helps in collecting each and every request in the form of an event and then place each event in a queue. Thus resulting in the generation of the Event Queue. Simultaneously, we have our event loop which iterates the events present in the Event Queue.
Also Read: What Is C Programming Language? Benefits and Career Advice
14. What are LTS releases of Node.js?
LTS stands Long Term Support version of Node.js that receives all the critical bug fixes along with security updates and performance improvements. These versions are supported for at least 18 months and mainly focus on stability and security. The modifications done to the LTS versions are restricted to the bug fixes, security upgrade, npm, and documentation updates, performance improvement, etc.
15. List down the major security implementations within Node.js?
Major security implementations in Node.js are:
- Authentications
- Error Handling
16. What do you understand by callback hell?
Callback Hell is also known as the Pyramid of Doom. It is a pattern caused by intensively nested callbacks which are unreadable and unwieldy. It typically contains multiple nested callback functions which in turn make the code hard to read and debug. It is caused by improper implementation of the asynchronous logic.
1 2 3 4 5 6 7 8 9 | async_A(function(){async_B(function(){async_C(function(){async_D(function(){....});});});}); |
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17. Explain libuv.
Libuv is a multi-platform support library of Node.js which majorly is used for asynchronous I/O. It was primarily developed for Node.js, with time it is popularly practiced with other systems like as Luvit, pyuv, Julia, etc. Libuv is basically an abstraction around libev/ IOCP depending on the platform, providing users an API based on libev. A few of the important features of libuv are:
- Full-featured event loop backed
- File system events
- Asynchronous file & file system operations
- Asynchronous TCP & UDP sockets
- Child processes
18. Explain the concept of middleware in Node.js?
In general, middleware is a function receives the Request and Response objects. In other words, in an application’s request-response cycle these functions have access to various request & response objects along with the next function of the cycle. The next function of middleware is represented with the help of a variable, usually named next. Most commonly performed tasks by the middleware functions are:
- Execute any type of code
- Update or modify the request and the response objects
- Finish the request-response cycle
- Invoke the next middleware in the stack
19. Explain the concept of URL module.
The URL module of Node.js provides various utilities for URL resolution and parsing. It is a built-in module that helps in splitting up the web address into a readable format:
1 | var url = require('url'); |
For example:
1 2 3 4 5 6 7 8 | var url = require('url');var q = url.parse(adr, true);console.log(q.host); //returns 'localhost:8082'console.log(q.pathname); //returns '/default.htm'console.log(q.search); //returns '?year=2019 and month=april'var qdata = q.query; //returns an object: { year: 2019, month: 'april' }console.log(qdata.month); //returns 'april' |
Overall, preparation is the key to success in a interview questions in Node JS . By studying the language, practicing coding, and researching the company and the position, you can present yourself as a qualified candidate and increase your chances of landing the job.
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