Summary of Node.js Questions and Answers

This document provides a collection of common questions and answers related to Node.js, an open-source, cross-platform JavaScript runtime environment. It is designed to help beginners understand key concepts and features of Node.js.

Key Concepts

What is Node.js?

• Definition: Node.js is a runtime environment that allows you to execute JavaScript on the server side.
• Built on: It uses the V8 JavaScript engine, which is developed by Google for Chrome.

Features of Node.js

• Asynchronous and Event-Driven: Node.js operates on a non-blocking I/O model, allowing multiple operations to be executed concurrently.
• Single-threaded: It uses a single-threaded model with event looping, making it efficient for I/O-heavy operations.
• NPM (Node Package Manager): A vast repository of libraries and modules that can be easily integrated into your projects.

Use Cases

• Web Development: Ideal for building fast and scalable network applications.
• Real-time Applications: Suitable for applications like chat apps and live updates due to its event-driven nature.

Common Questions

1. How to create a simple HTTP server in Node.js?

Example:

const http = require('http');

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

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

This code snippet creates a basic HTTP server that listens on port 3000 and returns "Hello World!" when accessed.

2. What is middleware in Express.js?

• Definition: Middleware functions are functions that execute during the request-response cycle in an Express application.
• Purpose: Used to perform tasks such as logging, authentication, parsing request bodies, etc.

3. How to handle errors in Node.js?

• Method: Use the try-catch statement for synchronous code and the .catch() method for promises.

Example:

const fs = require('fs');

fs.readFile('file.txt', 'utf8', (err, data) => {
  if (err) {
    console.error('Error reading file:', err);
    return;
  }
  console.log(data);
});

Conclusion

The document serves as a helpful resource for beginners looking to grasp the fundamentals of Node.js. It covers various essential topics such as creating a server, understanding middleware, and handling errors, providing practical examples to illustrate these concepts.