Question 1

What's the difference between Node.js and JavaScript?

Accepted Answer

JavaScript is a scripting language used along with HTML and CSS to add interactivity and functionality to your web page. Node.js is a JavaScript run-time engine that allows JavaScript programs to run outside the browser for client-side development.

Question 2

What is the role of modules in JavaScript?

Accepted Answer

A module is nothing but a reusable block of code that can be exposed and imported from one file to another. It can be a single file or multiple files or folders. It encourages code reusability and minimizes the complexity of code.

Question 3

What is the Node Package Manager (NPM) in Node.js?

Accepted Answer

It is the default package manager that provides access to its extensive ecosystem. Where developers can reuse packages and modules to build applications. With NPM, managing project dependencies, installing and updating packages, and sharing the packages with the community is super easy.

Question 4

What is asynchronous programming?

Accepted Answer

Asynchronous enables the non-blocking execution of code to handle multiple tasks simultaneously. It takes care of the I/O operations, including reading and writing files and network requests, without blocking the entire application.

Question 5

What does CLI mean in Node.js?

Accepted Answer

It is a command-line interface (CLI). In node.js CLI, helps automate tasks by leveraging its 900000 packages. Also, developers can easily differentiate proposed packages within the ecosystem.

Question 6

Write steps to check whether Node.js is installed or not.

Accepted Answer

The first step is to install NPM.

Once installed, simply type simple commands and open the Windows command prompt.

Then open the command-line tool line Babun, Powershell, ConEmu, etc.

After that,type node-v. Now your current version of Node.js will be displayed.

Question 7

Differentiate between the cluster and child_process modules.

Accepted Answer

A cluster runs more than one node in a master program for one runtime. But the child process starts with a new script on the system, though they're similar in some ways and different in the way they execute.

Question 8

How does the node use the CPU when it uses only a single thread?

Accepted Answer

Although node.js is single threaded, a node refers to a topology that can communicate with more than one node. This communication between the two nodes makes use of all CPUs. Therefore, this helps to maximize CPU efficiency.

Question 9

What are the types of npm modules in node.js?

Accepted Answer

The following are the types of NPM modules:   
 MongoDB and Mongojs  
 Redis, Lodash  
 forever  
 Express  
 connect socket.io and socket.js  
 pug,  
 bluebird  
 moment

Question 10

What does REPL stand for?

Accepted Answer

It stands for Read-Eval-Print-Loop.

Question 11

Is Node.js a framework?

Accepted Answer

No, it is not. It is a JavaScript runtime environment that runs under the engine of V8.

Question 12

What does the error-first callback do in Node.js?

Accepted Answer

It checks whether the code is working properly or not and then verifies it so that there are no more errors. Error-first callbacks send the error first, followed by the related data of that error.

Question 13

What does callback hell mean in Node.js?

Accepted Answer

The main role of callback hell is to return a complex and unreadable callback.

Question 14

What are the arguments that async.queue takes as input?

Accepted Answer

Task function and concurrency value are the two arguments that async.queue takes as an input.

Question 15

What is the difference between Angular.js and Node.js?

Accepted Answer

Angular.js is a framework for JavaScript used for creating highly active client-side web applications. Node.js is a cross-platform run-time environment for JavaScript used for creating scalable server-side networking applications.

Question 16

List some companies that use node.js.

Accepted Answer

The following are big companies that use node.js:   
* Netflix  
* Uber  
* eBay  
* Medium  
* NASA  
* Trello  
* PayPal  
* LinkedIn  
* Yahoo  
* Mozilla

Question 17

What are the promises in Node.js?

Accepted Answer

Promises are used to handle asynchronous operations in an organized way. It tells whether an asynchronous operation is completed or failed.

Question 18

What is the role of the emitter?

Accepted Answer

The emitter's job is to establish communication between two nodes.

Question 19

Write a simple program in Node.js.

Accepted Answer

var http = require('http'); 
  
http.createServer(function (req, res) { 
   res.writeHead(200, {'Content-Type': 'text/html'}); 
   res.end('Hello World!'); 
 }).listen(8080);

source:w3school

Question 20

Define events

Accepted Answer

The events can be any task or activity carried out in the Node.js application. Let's say you're opening the file. This is also an event, and like closing a file, this is also an event.

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