Express installation and setup

Introduction

Express helps you build web servers easily. Installing and setting it up lets you start making websites or APIs quickly.

You want to create a simple web server to serve web pages.

You need to build an API to send and receive data.

You want to handle user requests like form submissions.

You want to learn how backend web servers work.

You want to add routing to your Node.js app.

Syntax

Express

npm install express

// In your JavaScript file:
import express from 'express';
const app = express();

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

Use npm install express to add Express to your project.

Import Express with import express from 'express'; when using ES modules.

Examples

This command installs Express in your project folder.

Express

npm install express

This creates an Express app you can use to define routes and middleware.

Express

import express from 'express';
const app = express();

This starts the server on port 3000 and logs a message when ready.

Express

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

Sample Program

This program sets up a basic Express server. When you visit http://localhost:3000/ in your browser, it shows "Hello, Express!".

Express

import express from 'express';

const app = express();

app.get('/', (req, res) => {
  res.send('Hello, Express!');
});

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

Important Notes

Make sure you run npm init -y first to create a package.json file.

Use node --experimental-modules or set "type": "module" in package.json to use ES module syntax.

Port 3000 is common for local development but you can choose any free port.

Summary

Express is installed using npm install express.

Import Express and create an app with express().

Start the server with app.listen(port) to handle requests.