Node.js Interview Questions and Answers

Node.js Interview Questions and Answers

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Best Node.js Interview Questions and Answers

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Q1) What is node.js?

Answer: 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?

Answer: 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?

Answer: 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.

Q4) What does event-driven programming mean?

Answer: 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?

Answer: Node.js can be used for the following purposes

  1. Web applications (especially real-time web applications)
  2. network applications
  3. Distributed systems
  4. general purpose applications

Q6) What is the benefit of using node.js?

Answer:

  1. This is the easiest way to create measurable network schemes
  2. Generally fast
  3. better integration
  4. everything that is not asynchronous
  5. There are almost no blocks

Q7) Types of API functions in Node.js?

Answer: Node.js has two types of API functions

  1. asynchronous, non-preventive operations
  2. synchronize and prevent operations

Q8) What is the control flow function?

Answer: 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.

Answer:

  1. Control the execution order
  2. Collect data
  3. integration limit
  4. Call the next step in the program

Q10) Why is Node.js single thread?

Answer: 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.

Q11) Does the node run in windows?

Answer: Yes, it does.

Q12) Can you access the DOM terminal?

Answer: No, you can not access the DOM terminal.

Q13) What are the tasks to do with the use of the Event Ring?

Answer:

  1.  I / O Functions
  2.  heavy calculation

Q14) Why do node.js quickly draw from JavaScript programmers?

Answer: Node.js draws attention because this is a loop-based server for JavaScript. Node.js gives the user

The ability to write javascript on the server, accessing the HTTP stack, file I / O, TCP etc.

And databases.

Q15) What are the two discussions that take async.queue?

Answer: Async.queue two arguments

  1.  task function
  2.  the value of the individual

Q16) What is an event cycle in Node.js?

Answer: Modify call events to activate and manipulate external events

Used. So, in the I / O calls, node.js can switch from another request.

Q17) Can you specify steps that can be single-tuned in Node.js?

Answer: You can async Node.js with the following steps

  1. First Class Activities
  2. Operational system
  3.  counters
  4.  Event loops

Q18) What is the benefit of Node.js?

Answer:

Pros:

  1.  If you do not have any CPU intensive computation in your application, you can create it with JavaScript, If you use JSON Storage Object DB, such as MonDO DB, above the database level below,
  2.  Crawlers receive a response from a complete HTML code, not a SEO friendship, Single page usage or a websockets app run over Node.js.

Cons:

  1. Any serious CPU calculation prevents the responsiveness of node.js, so there is a distorted base Best approach.
  2. Using relational databases associated with Node.js is considered less favorable

Q19) How does Node.js violate the issue of blocking I / O operations?

Answer: Node.js uses the event-based model at its center using an event loop to solve this problem

Texts.

Q20) What is the difference between Node.js against Ajax?

Answer: The difference between Node.js and Ajax is AJAX (short for Asynchronous JavaScript and XML)

Client-side technology is often used to update the contents of the page without refreshing.

When Node.js server software javascript, server software is used for developing. Node.js can not be run

In the browser but through the server.

Q21) What are the challenges with Node.js?

Answer: On the technical side, it’s a bit of a challenge to Node.js to have a process

A scalable thread on a multi-core server.

Q22) What does it mean to be “block-prevention” in node.js?

Answer: In “Node.js”, “Block-resistance” refers to blocking its IO. The moment uses “libuv” to handle its IO a

Site-acoustic way In windows, it utilizes complete ports for Unic, which uses epoll or kqueue

Creates an unblock request and puts it within the so-called event ring on the request

JavaScript ‘request’ in the main javascript thread.

Q23) What is the command used for node.js to export external libraries?

Answer: The command to import external libraries is “required”, for example, “var http = required (” http “).

This will load the HTTP library and the single exported item through the http variable.

Q24) Do you specify the structure commonly used in node.js?

Answer: “Express” is a common configuration used in node.js

Q25) What is ‘Callback’ in Node.js?

Answer: The callback function is used in node.js to handle many of the server’s requests. If you have

The server is going to take a long time to read a big file and if you do not want to get a server When dealing with other requests, read that big file and repeat the function. Call the backup function allows the server to cope with the pending request first and a function is called when it is present Concluded.

Q26) What is the relationship of Node.js with JavaScript?

Answer:

  1. Node.js is not a javascript framework, and many of its modules are written here.
  2. It allows developers to create new modules for JavaScript.
  3. Node.js is a virtual machine, which makes JavaScript to get a high output as a scripting language.

Q27) What is the difference between Node.js and Ajax?

Answer: Although AJAX is a client-technology technology, Node.js is a server-side JavaScript environment.

Q28) Explain the word I / O in the context of Node.js.

Answer: I / O has input and output. It is used to access anything outside the application. Once the I / O application is rejected it will be loaded into machine memory to enable programs.

Q29) Node.js state that can be used.

Answer:

  1. Web applications
  2. Network applications
  3. Distributed systems
  4. General purpose applications

Q30) What are two types of API functions in Node.js?

Answer: Disruptive, non-stop functioning and synchronization will prevent operations.

Q31) List the tools and IDEs used for Node.js.

Answer:

  1. The game
  2. Nodeclipse Enide Studio
  3. Jet Bartons West Star
  4. JetBrains InteliJ Idea
  5. MS Visual Studio
  6. NoFLo

Q32) Explain the role of the request process in Node.js.

Answer: In Node.js, the request function is used to satisfy many requests from the server. If there is a large file that will take long for the server to perform, you can make a request to ensure that other requests to the server are uninterrupted.

Q33) What is a bug – first request?

Answer: Error-to-use invitations are mainly used to add errors and data. By default, the first argument always refers to a bug, and the user must check if there is anything wrong with it.

Q34) The difference between functional and programmer errors in the context of Node.js.

Answer: Functional errors are not real bugs. They are computer errors, such as “request time” or “hardware error”. Programming errors are the actual errors in the index.

Q35) What structure is commonly used in Node.js?

Answer: The most commonly used Node.js configuration is “Express”.

Q36) Event-driven programming definition.

Answer: This program is a programming example that is characterized by events by news programs of other programs.

Q37) What are two sections of event driven programming?

Answer: Event selection and event handling are two parts of event driven programming.

Q38) List some of the benefits of using Node.js.

Answer:

  1. Ability to develop strategic plans
  2. Increased coordination
  3. Incomparable skills

Q39) Explain the control flow function.

Answer: It is a common area code running simultaneously between multiple asynchronous function calls.

Q40) List the instructions in the Control Flow process.

Answer: Limit concurrency is the next program call to collect data to control the order of execution.

Q41) Can a user access the DOM?

Answer: No, you can not access the DOM.

Q42) How can I access the last expression in Node.js?

Answer: Underline the last expression (_) to use the character.

Q43) What is the biggest drawback of Node.js?

Answer: The biggest disadvantage is the fact that it is challenging to process a single thread to measure multiple core servers.

Q44) Explain REPL at Node.Js

Answer: REPL REAL REAL Print Loop It accepts, evaluates, and prints results. REPL provides the UNIX / Linux shell or a window console, which will include the command and the system, as a result we will respond to the output. REPL performs the following tasks.

Q45) What is the request on Node.Js?

Answer: We can call “callback” a coherent equivalent to a call. Node.js utilizes callbacks at large and stimulates the end of the given task. All APIs in Node.js are written to support callbacks.

Q46) What is a foot blade?

Answer: Initially, you can report a reputation after you know about it. Anger hell is very hard towers, which is hard to read and maintain.

Q47) How to Avoid Calling on Node.Js

Answer: Node.js uses a single threaded event indoors to activate the order processes. But if this approach is running longer than expected, it will prevent the whole process.

Q48) How many streams are there in Node.Js?

Answer:

  1. <Reader> – This is a stream that can be used for reading activity.
  2. <Write> – It makes writing function easier.
  3. <Duplex> – This stream can be used to read and write both.
  4. <Transform> – This is a double stream format, which calculates the available input.
  5. <data> – Removes this event when there are data available to read.
  6. <end> – The stream burns this event when there is no more data to read.
  7. <error> – This event gun when there is no error reading or writing data.
  8. <Filler> – It will fill this event after clearing all the data on the base system.

Q49) Which of the below statement/s are true about Node.js?

  1. Node is completely written in JavaScript
  2. Node supports modular JavaScript

Answer: Only 2 is true

Q50) A node application developer is working on an application wherein he has to send a message back to the client from the server. Which among the below method can he use to implement the same?

Answer: write(“message”);

Q51) Consider a module index.js which is placed inside the mymodule folder. Consider another index.js  Which is placed outside the mymodule folder and given below is its content: var mymodule=require(‘./mymodule’);

mymodule();

What will be the output if the outside index.js is executed?

Answer: executes successfully

Q52)Consider the below code snippet:

 url = require(“url”);

function onRequest(request, response) { var query=___________________; var name=querystring.parse(query)[“un”]; response.writeHead(200, {“Content-Type”: “text/plain”}); response.write(“Hello “+name);}

Answer: parse(request.url).query

Q53) on (____, function(data){var data1=data; }); Fill the missing code from the options below to get the data from the client using post request.

Answer: data

Q54) Which of the below are built-in events in Node?

Answer: data, end

Q55) url = require(“url”);http.createServer(function(request, response) { var url_parts = _________; if(url_parts.pathname==”/login”)  write(“Login Page”);  response.end(); } Fill the missing code from the below options.

Answer: parse(request.url)

Q56) After successfully installed the Node.js on the developer system which of the below command   can be used to check the version of Node.

Answer: Node –v

Q57) Which of the following types of applications can be built in node.js?

Answer: Web application, RESTFUL Service, Chat application

Q58) State TRUE or FALSE – The callback function is a way of synchronous coding execution and          get executed following a blocking I/O operation

Answer: FALSE

Q59) A node.js application is working in an application, wherein he has to send a response back to     the client from the server. Which among the below methods can be used to implement the same?

Answer: end(“message”);

Q60) Consider a module test1.js which is placed inside my module folder. Consider another test2.js  file which is placed outside my module folder and given below is its content. What will be the output if the outside test2.js is executed

Var  mymodule = require(“./mymodule”); mymodule();

Answer: Throws exception

Q61) Consider the code snippet below:

request.on(——, function(data) { var data1 = data;}); fill the missing code to get the data from the client using POST request.

Answer: data

Q62) Which of the following is true about EventEmiiter.on()?

Answer: The on() method is used to bind an event handler with the event.

Q63) STATE TRUE or FALSE – The ‘querystring’ module in node.js provides methods for parsing and formatting URL query strings.

Answer: TRUE

Q64) After successfully installed the Node.js on the system which of the below command can be used to update NPM version?

Answer: Npm install npm

Q65) Why node.js is a single threaded/multi-threaded?

Answer: js is a single-threaded for asynchronous processing. With the help of asynchronous processing on a single-thread under typical web loads, leads more the performance and the scalability can be achieved thread-based implementation.

Q66) Which one is not a method of EventEmiiter class in Node.js?

Answer: raw

Q67) Which of the following is true that the EventEmitter.emit() function in the Node.js?

Answer: emit() method is used to fire an event.

Q68) If the URL is http://localhost:7777/login?name=Chitra, the url pathname prints

Answer: Login

 Q69) Which of the most popular framework of Node for implementing routing?

Answer: Express

Q70) A node application developer is working on a project specification wherein she needs to read the content of a file while performing other operations. When function from the below will she select to perform the same?

Answer: readFile

Q71) What is the responsibility for the writeFile method in FS module?

Answer: It replaces the file if it already exists.

Q72) Guess the output of below code snippet?

var fs = require(‘fs’);

fs.readFIle(‘demo.txt”, “UTF8”, (err, content) => console.log(content); });

var data = fs.readFileSyce(“demo2.txt”); console.log(data.toString());

Answer: Data from demo2.text file data from demo1.txt file

Q73)Streams should be preferred in which of the following situations

Answer:

  • File uploads in real time
  • To perform live streaming of video

Q74) John, a software developer wants to compress the file using node.js. Which of the following built-in modules he can use to achieve his requirement?

Answer: Zlib

Q75) Consider the code snippet

var  readStream = fs.createReadStream(“test.txt”);

var writeStream = fs.createWriteStream(“text2.txt”);

fill in the code to write the date to the destinations.

Answer: pipe(writeStream);

Q76) The statement is true regarding the TCP server?

Answer: TCP server can send data to the client

Q77) Which method is used to create a TCP server?

Answer: createServer()

Q78) Which built-in module can be used for socket programming?

Answer: Net

Q79) Which of the mode of installation is better to install any package which has an application dependency?

Answer: local

Q80) The correct statement regarding npm

Answer:

  • Npm is the default package manager bundled with node.js
  • Open-source developers use npm to share and borrow packages
  • Packages are structured to keep track of dependencies and version in npm

Q81) A node application developer is working on a project requirement wherein he needs to have a node module to be available across the command line. Which among the command will he use to install the module?

Answer: npm install modulename –g

Q82) John wants to check the version of NPM. Which command line he can use to meet his requirement?

Answer: npm –v

Q83) Which of the following is a drop-in replacement of NPM?

Answer: Yarn

Q84) The package.json file can contain which of the following information?

Answer:

  • Module name
  • License

Q85) Which of command is used to create the package.json file?

Answer: npm init

Q86) The “npm install” command installs the dependencies present in package.json file in the node_modules folder. Is state true or false?

Answer: Yes

Q87)Consider the code below written for connection the MYSQL database

var client = sql.createConnection({ host: “localhost”, user: “root” });

client.connect();

client.query(“use bookDB”);

which is true in above code?

Answer: Throws error if the DB does not exist

Q88) Select the object data modeling library for MongoDB used in node application?

Answer: Mongoose

Q89) A node application developer is working on a requirement wherein she needs to connect to another web application to execute a specific logic. Which among the will select to do the same?

Answer: Make a rest call to the other application using restler module

Q90) A node application developer is working on a project specification wherein she needs to save the data to the database using another application. Which among to do the same?

Answer: Make an HTTP post request to a restful web service.

Q91) A node application developer is working on a requirement wherein she needs to create a child process to execute a set of code in her application. Which will she make use to achieve the same?

Answer: exec()

Q92) A node application developer is working on an application, wherein she has to do load balancing between child processes. Which node module will she select to implement the same?

Answer: Cluster

Q93) ———- method the specialized form of spawn() method to create the child process?

Answer: fork()

Q94) Harry, a node application developer wants to run a python script from node.js. Is it possible for him to achieve his requirement using chid process module?

Answer: Yes

Q95) Which command is used to inert the breaking point in a node application?

Answer: debugger

Q96) Which is used to give a graphical user interface to perform node application debugging?

Answer: V8 inspector

Q97) Which is used to watch the changes occurring inside a given directory and restart the node application after each change?

Answer: Nodemon

 Q98) js asynchronous/ synchronous?

Answer: Asynchronous

Q99) Node js single threaded/multi-threaded?

Answer: Single-threaded

Q100) Is Node.js is front end/back end?

Answer: js is not front end or back end. It is a combination of the runtime environment and javascript library

Q101) Is it possible to evaluate expressing in Nodejs?

Answer: Yes, it is possible to evaluate the expression

Q102) What do you mean by local dependencies?

Answer: NPM installation can be any dependency in local. But local mode means the package of installation in a node_module folder. Here deployment is accessible by require();

Q103)what do you know about package.json?

Answer: It sits in the root directory of node application which is used to define properties.

Q104)List attribute of package.json?

Answer:

  • Name
  • Version
  • Description
  • Author
  • Homepage
  • Repository
  • Main
  • Keywords
  • Contributors
  • Dependencies

Q105) Diff between Angularjs & nodejs ?

Answer:

  • Angularjs – It’s a web application framework
  • NodeJs – It’s a runtime system.

 

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