Node.js Interview Questions and Answers

Node.js Interview Questions and Answers

by GangBoard Admin, April 3, 2019

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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?


  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.


  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?


  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?



  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.


  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


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


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


  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.


  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.


  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.


  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?


  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.

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