Node.js Basics

Node.js is a JavaScript runtime built on Chrome's V8 engine that allows you to run JavaScript on the server side. It enables building scalable network applications with event-driven, non-blocking I/O models.

Key Features of Node.js

• Event-driven and Asynchronous: Handles many connections concurrently without blocking.
• Single-threaded: Uses a single thread with event looping for handling requests efficiently.
• Built-in Modules: Provides modules like fs for file system, http for server, and path for file paths.
• NPM: Comes with Node Package Manager for managing third-party libraries.

Running JavaScript with Node.js

To run a JavaScript file using Node.js, use the terminal command:

node filename.js

Example hello.js:

console.log('Hello from Node.js');

Commonly Used Built-in Modules

Importing Modules

Use require() to include modules in Node.js:

const fs = require('fs');
const path = require('path');

Creating a Simple HTTP Server

One of the first things to try in Node.js is creating a basic web server:

const http = require('http');

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

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

Summary

• Node.js allows running JavaScript outside the browser for backend development.
• Use node filename.js to run scripts.
• Core modules like fs and http provide essential functionality.
• Modules are loaded using require().
• Build servers easily with the http module.