30+ Node.js Interview Questions for Web Development

Node.js Interview Questions

1. What is Node.js?

Node.js is Server-side scripting which is utilized to assemble adaptable projects. It is a web application system based on Google Chrome's JavaScript Engine. It keeps running inside the Node.js runtime on Mac OS, Windows, and Linux without any changes. This runtime encourages you to execute a JavaScript code on any machine outside a program.

2. Is Node.js free to use?

  • Indeed. It is discharged under MIT permit and is allowed to utilize.
  • Is Node a single threaded application?
  • Indeed. Hub is a solitary strung application with occasion circling.

3. What is the purpose of Node.js?

These are the accompanying reasons for Node.js: 
  • Constant web applications 
  • System applications 
  • Dispersed frameworks 
  • Broadly useful applications

4. What are the advantages of Node.js?

Following are the principle focal points of Node.js: 
  • Node.js is offbeat and occasion driven. All API?s of Node.js library are non-blocking, and its server doesn't trust that an API will return information. It moves to the following API subsequent to calling it, and a notice component of Events of Node.js reacts to the server from the past API call. 
  • Node.js is quick since it expands on Google Chrome?s V8 JavaScript motor. Its library is quick in code execution. 
  • Node.js is single strung yet exceedingly adaptable. 
  • Node.js gives an office of no buffering. Its application never cushions any information. It yields the information in lumps.

5. Explain Node.js web application architecture?

A web application recognizes into 4 layers: 
Customer Layer: The Client layer contains internet browsers, portable programs or applications which can make a HTTP ask for to the web server.
Server Layer: The Server layer contains the Web server which can block the demand made by customers and pass them the reaction.
Business Layer: The business layer contains application server which is used by the web server to do required handling. This layer associates with the information layer by means of database or some outer projects.
Information Layer: The Data layer contains databases or any wellspring of information.

6. What do you understand by the term I/O?

I/O represents information and yield. It gets to anything outside of your application. It stacked into the machine memory to run the program, when the application begins.

7. How many types of API functions are available in Node.js?

There are two types of API functions in Node.js:
  • Asynchronous, Non-blocking functions
  • Synchronous, Blocking functions

8. What is error-first callback?

Mistake first callbacks are utilized to pass blunders and information. In the case of something turns out badly, the software engineer needs to check the primary contention since it is dependably a mistake contention. Extra contentions are utilized to pass information.

9. What is an asynchronous API?

Every one of the API's of Node.js library are offbeat methods non-blocking. A Node.js based server never trusts that an API will return information. The Node.js server moves to the following API in the wake of calling it, and a warning component of Events of Node.js reacts to the server for the past API call.

10. How can you avoid callbacks?

  • To stay away from callbacks, you can utilize any of the accompanying alternatives: 
  • You can utilize modularization. It breaks callbacks into free capacities. 
  • You can utilize guarantees. 
  • You can utilize yield with Generators and Promises.

11. Does Node.js provide Debugger?

To stay away from callbacks, you can utilize any of the accompanying alternatives: 
  • You can utilize modularization. It breaks callbacks into free capacities. 
  • You can utilize guarantees. 
  • You can utilize yield with Generators and Promises.

12. What is a control flow function?

Control stream work is a conventional bit of code that keeps running in the middle of a few offbeat capacity calls.

13. How "Control Flow" controls the functions calls?

The control stream does the accompanying activity: 
  • Control the request of execution 
  • Gather information 
  • Point of confinement simultaneousness 
  • Call the following stage in a program

14. Is it possible to access DOM in Node?

No, it is not possible to access DOM in Node.

15. What types of tasks can be done asynchronously using the event loop?

  • I/O operations
  • Heavy computation
  • Anything requiring blocking

16. What is REPL in Node.js?

The control stream does the accompanying activity: 
  • Control the request of execution 
  • Gather information 
  • Point of confinement simultaneousness 
  • Call the following stage in a program
  • Explain the tasks of terms used in Node REPL.
Following are the terms utilized in REPL with their characterized assignments: 
Peruse: It peruses client's information; parse the contribution to JavaScript information structure and stores in memory.
Eval: It takes and assesses the information structure.
Print: It is utilized to print the outcome.
Circle: It circles the above order until client press ctrl-c twice to end.

17. Is it possible to evaluate simple expressions using Node REPL?

Yes. You can evaluate simple expressions using Node REPL

18. What is npm? What is the main functionality of npm?

Node Package Manager stands for npm. The two main functionalities of npm are as follows: Online repositories for packages / modules node.js that can be searched on the search.nodejs.org command line to install packages, manage versions and manage dependencies of packages Node.js.

19. What tools can be used to assure a consistent style in Node.js?

Following is a rundown of apparatuses that can be utilized in creating code in groups, to uphold a given style manage and to find basic blunders utilizing static investigation.
  • JSLint 
  • JSHint 
  • ESLint 
  • JSCS

20. What is the difference between operational and programmer errors?

Operational mistakes are not bugs, yet make issues with the framework like demand timeout or equipment disappointment. Then again, software engineer mistakes are genuine bugs.

21. What is the use of a buffer class in Node.js?

The Node.js gives Buffer class to store crude information like a variety of whole numbers yet relates to a crude memory portion outside the V8 pile. It is a worldwide class and can be gotten to in an application without bringing in a cradle module. Support class is utilized in light of the fact that unadulterated JavaScript isn't perfect with paired information. In this way, when managing TCP streams or the document framework, it's important to deal with octet streams.

22. What is the role of assert in Node.js?

The Node.js Assert is an approach to compose tests. It gives no criticism when running your test except if one fizzles. The attest module gives a basic arrangement of affirmation tests that can be utilized to test invariants. The module is proposed for inward use by Node.js, however can be utilized in application code by means of require ('declare')

23. What are the streams in Node.js?

The Streams are the items that encourage you to peruse information from a source and compose information to a goal. There are four sorts of streams in Node.js:
  • Coherent: This stream is utilized for perusing activities. 
  • Writable: This stream is utilized for compose activities. 
  • Duplex: This stream can be utilized for both perusing and compose activities. 
  • Change: It is a sort of duplex stream where the yield processes as indicated by info.

24. What is event-driven programming in Node.js?

In Node.js, occasion driven programming implies when Node begins its server, it starts its factors, announces capacities and afterward trusts that an occasion will happen. It is one reason why Node.js is truly quick contrasted with other comparative advancements.

25. What is the difference between events and callbacks in Node.js?

In spite of the fact that, Events and Callbacks appear to be comparative the distinctions lies in the way that callback capacities are considered when a nonconcurrent work restores its outcome while occasion taking care of takes a shot at the onlooker design. At whatever point an occasion gets terminated, its audience work begins executing. Node.js has different in-constructed occasions accessible through the occasions module and EventEmitter class which is utilized to tie occasions and occasion audience members.

26. What is the Punycode in Node.js?

The Punycode is an encoding punctuation which is utilized to change over Unicode (UTF-8) series of characters to ASCII series of characters. It is packaged with Node.js v0.6.2 and later forms. On the off chance that you need to utilize it with different Node.js adaptations, at that point use npm to introduce Punycode module first. You need to utilized require ('Punycode') to get to it.

27. What does Node.js TTY module contains?

The Node.js TTY module contains tty.ReadStream and tty.WriteStream classes. By and large, there is no compelling reason to utilize this module specifically. You need to utilized require ('tty') to get to this module.