🌐 Introduction to Express.js

Express.js, or simply Express, is a fast, minimalist web framework for Node.js. It provides a robust set of features for building web applications and APIs, making it the de facto standard for server-side development in the Node ecosystem.

Express simplifies handling HTTP requests and responses by offering:

• Routing: Define clean URL patterns and handle different HTTP methods with ease.
• Middleware support: Add functionality to your app (e.g., logging, authentication, parsing JSON) by chaining reusable functions.
• Template engine integration: Render dynamic HTML pages.
• Simplified error handling: Centralized error middleware for graceful responses.

Since it’s lightweight and unopinionated, Express gives you full control over your app’s architecture, allowing you to build anything from a small REST API to a complex, full-featured web server.

Express powers many popular Node.js frameworks (like Sails, NestJS) and is widely used by developers around the world for its simplicity and flexibility.

📘 Express.js Route Example Explained

const express = require('express');
const app = express(); // creates server

app.get('/home', (req, res) => {
  res.send("Home");
});

app.get('/about', (req, res) => {
  res.send("About");
});

app.listen(3000, () => {
  console.log("server is running on port 3000.");
});

🟢 Line-by-line Breakdown

✅ 1. Import Express

const express = require('express');

• Loads the Express library so you can use it in your app.