Node JS Practical Interview Questions & Answers

Are you preparing for a Node JS interview? Here are some practical interview questions and answers that will help you ace your interview:

1. What is Node JS?

Node JS is a server-side platform built on Google Chrome’s JavaScript Engine (V8) for easily building fast and scalable network applications. It uses an event-driven, non-blocking I/O model that makes it lightweight and efficient.

2. What are the core modules in Node JS?

Node JS has several core modules that provide essential functionality. Some of the core modules include:

• http: for creating web servers and clients
• fs: for file system operations
• path: for handling file paths
• os: for getting information about the operating system

3. What is npm and what is its use in Node JS?

npm stands for Node Package Manager and is the default package manager for Node JS. It is used to install, manage, and publish packages of reusable code. It also allows you to manage project dependencies and run scripts.

4. What is the difference between synchronous and asynchronous programming in Node JS?

In synchronous programming, the code is executed in a sequential manner, one after the other. In asynchronous programming, tasks run concurrently and do not block the execution of other tasks. In Node JS, asynchronous programming is used to handle I/O operations, making the application more efficient.

5. How can you handle errors in Node JS?

In Node JS, errors can be handled using try-catch blocks, error-first callbacks, and the use of error event emitters. It is important to handle errors properly to ensure that the application remains stable and reliable.

6. What is the event loop in Node JS?

The event loop is a core concept in Node JS that allows the execution of non-blocking I/O operations. It continuously checks for tasks in the event queue and executes them in a loop. This allows Node JS to handle multiple tasks simultaneously without blocking the execution of other tasks.

7. How can you create a simple HTTP server in Node JS?

You can create a simple HTTP server in Node JS using the http module. Here is an example:

const http = require('http');

const server = http.createServer((req, res) => {
  res.writeHead(200, {'Content-Type': 'text/plain'});
  res.end('Hello, World!n');
});

server.listen(3000, 'localhost', () => {
  console.log('Server running at http://localhost:3000/');
});

8. What is callback hell in Node JS?

Callback hell refers to the nesting of multiple callbacks within each other, leading to code that is difficult to read and maintain. This can happen when handling asynchronous operations in Node JS. To avoid callback hell, you can use promises, async/await, or modularize your code.

These are some of the practical interview questions and answers for Node JS. Make sure to prepare and practice these concepts before your interview to showcase your knowledge and skills in Node JS.