Hexaware – Node JS Interview Questions

Here is the list of Node JS Interview Questions which are recently asked in Hexaware company. These questions are included for both Freshers and Experienced professionals. Our Node JS Training has Answered all the below Questions.

1. Which is the first argument typically passed to a Node.js callback handler?

The first parameter of the callback is the error value. If the function hits an error, then they typically call the callback with the first parameter being an Error object. If it cleanly exits, then they will call the callback with the first parameter being null and the rest being the return value(s).

2. What are the functionalities of NPM in Node.js?

Node Package Manager provides two main functionalities:

It provides online repositories for node.js packages/modules which are searchable on search.nodejs.org.
It also provides command line utility to install Node.js packages, do version management and dependency management of Node. js packages.

3. What is the difference between Node.js and Ajax?

The difference between Node.js and Ajax is that, Ajax is a client side technology, often used for updating the contents of the page without refreshing it while Node.js is Server Side JavaScript, used for developing server software.

4. Explain chaining in Node.js.

Chaining in Node.js can be achieved using the asyncnpm module. There are two most commonly used methods for chaining functions provided by the async module: parallel and series.

5. What are “streams” in Node.js? Explain the different types of streams present in Node.js.

Streams are one of the fundamental concepts of Node.js and are a type of data-handling methods, used to read or write input into output sequentially. Streams are used to handle reading/writing files or exchanging information in an efficient way.

There are four fundamental stream types in Node. js: Readable, Writable, Duplex, and Transform streams.

6. What are the exit codes in Node.js? List some exit codes.

Exit codes are the specific codes that can be used to end a process. Some of the examples of exit codes are Uncaught Fatal Exception, Fatal Error, Non-function Internal Exception Handler, Internal Exception handler Run-Time Failure, Internal JavaScript Evaluation Failure, etc.

7. What are Globals in Node.js?

While in browsers the global scope is the window object, in nodeJS the global scope of a module is the module itself, so when defining a variable in the global scope of nodeJS module, it will be local to this module.

<Object> the global namespace object.

8. What is the difference between AngularJS and Node.js?

AngularJS is a JavaScript framework, whereas NodeJS is a cross-platform runtime environment. As a client-side JavaScript framework, AngularJS Angular enables developers to create dynamic web applications based on model-view-controller (MVC) architectural pattern and using HTML as a template language.

9. What is “callback hell” and how can it be avoided?

Callback Hellis an anti-pattern seen in code of asynchronous programming. It is a slang term used to describe and unwieldy number of nested “if” statements or functions. If you are not expecting your application logic to get too complex, a few callbacks seem harmless.

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10. How does Node.js handle child threads?

Node.js is a single-threaded language which uses the multiple threads in the background for certain tasks as I/O calls but it does not expose child threads to the developer.

11. For what require() is used in Node Js ?

Require() is a built-in function to include external modules that exist in separate files. It reads a JavaScript file, executes it, and then proceeds to return the export object.

12. Explain module.exports in Node Js ?

Exports is the object that returned as the result of a require call. The exports variable is initially set to that same object (i.e. it's a shorthand "alias"), so in the module code you would usually write something like this: let myFunc1 = function() { ... }; let myFunc2 = function() { ... }; exports.

13. Is Node Js Single-threaded ?

Node.js is single-threaded similar to JavaScript but not purely JavaScript code which implies things that are done asynchronously like network calls, file system tasks, DNS lookup, etc.

14. What are events ?

Node.js has an event-driven architecture which can perform asynchronous tasks. It has 'events' module which emits named events that can cause corresponding functions or callbacks to be called.

15. Explain event loop in Node Js ?

The event loop is what allows Node.js to perform non-blocking I/O operations that despite the fact that JavaScript is single-threaded and by offloading operations to the system kernel whenever possible. Since most modern kernels are multi-threaded, they can handle multiple operations executing in the background.

16. What Are The Key Features Of Node.Js?

Features of Node.js

Asynchronous and Event Driven
Very Fast
Single Threaded but Highly Scalable
No Buffering
License

17. What IDEs Can You Use For Node.Js Development?

js, Angular. js, HTML, CSS, JavaScript, Java, React, and more. With so many built-in development aids, database tools, version control systems, and decompiler, IntelliJ IDEA is the best IDE for Node js application development.

18. Explain How Does Node.Js Work?

Node.js is the JavaScript runtime environment which is based on Google's V8 Engine i.e. with the help of Node. It can run the JavaScript outside of the browser which is single-threaded, based on event-driven architecture, and non-blocking based on the I/O model

19. Explain REPL In Node.Js?

REPL stands for READ, EVAL, PRINT, LOOP is a computer environment similar to Shell (Unix/Linux), command prompt and useful in writing and debugging the codes.Node comes with the REPL environment when it is installed. System interacts with the user through outputs of commands/expressions used.

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TOP MNC's NODE JS INTERVIEW QUESTIONS & ANSWERS

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Hexaware Node JS Interview Questions