Setting Up Express.js

To start developing applications with Express.js, you need to set up your development environment and create a basic Express project.

1. Prerequisites

Before setting up Express.js, make sure you have:

• Node.js installed (v14 or later recommended)
  Check installation:

• node -v
  npm -v
  

• A code editor, like VS Code.

2. Create a New Project

1. Create a project folder:

1. npm init -y
   

   This creates a package.json file with default settings.

3. Install Express.js

Install Express using npm:

npm install express

Optional: Install nodemon for auto-restarting the server during development:

npm install --save-dev nodemon

4. Create the Entry File

Create a file named app.js (or index.js) in your project folder:

// Import express
const express = require('express');
const app = express();
const port = 3000;

// Define a basic route
app.get('/', (req, res) => {
  res.send('Hello, Express.js!');
});

// Start the server
app.listen(port, () => {
  console.log(`Server running at http://localhost:${port}`);
});

5. Add a Start Script (Optional)

In package.json, update the scripts section to use nodemon:

"scripts": {
  "start": "node app.js",
  "dev": "nodemon app.js"
}

• Run normally:

• npm run dev
  

6. Test the Server

1. Open your browser and go to:

1. Hello, Express.js!
   

7. Next Steps

After setting up Express.js, you can start exploring:

• Routing – Define endpoints for GET, POST, PUT, DELETE.

• Middleware – Handle requests, authentication, logging, error handling.

• Template Engines – Render dynamic HTML pages.

• REST APIs – Build backend APIs to serve frontend applications.

mkdir express-app
cd express-app

npm start

http://localhost:3000