Express.js Basic App

Creating a basic Express.js application is quick and easy. Below is a step-by-step guide to building a simple web application using Express that handles HTTP requests and returns responses.

 

Key Features of a Basic Express App

• Handles HTTP requests: The app listens for HTTP requests and sends responses based on the routes defined.
• Minimal setup: With Express, you only need a few lines of code to set up a basic web server.
• Middleware support: You can add custom middleware for tasks like logging, authentication, or handling errors.

 

Steps to Create a Basic Express App

Set up a New Node.js Project
If you haven't already created a Node.js project, initialize it by running:

npm init -y

Install Express
To install Express, use the following npm command:

npm install express --save

Create the Application File
Create a file called app.js (or another name of your choice), and write the following code:

const express = require('express');
const app = express();

// Define a route for the home page
app.get('/', (req, res) => {
    res.send('Welcome to Express!');
});

// Define a route for another page
app.get('/about', (req, res) => {
    res.send('This is the About page');
});

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

Run the Application
To run the application, execute the following command in your terminal:

node app.js

This will start the Express server, and the message Server is running on port 3000 will appear in your terminal.

Test the Routes
Open your browser and visit the following URLs:

• http://localhost:3000/ to see the "Welcome to Express!" message.
• http://localhost:3000/about to see the "This is the About page" message.

Optional: Add Middleware for Logging
You can add middleware to log the incoming requests. Add this code before the route definitions:

app.use((req, res, next) => {
    console.log(`${req.method} request to ${req.url}`);
    next(); // Pass control to the next middleware
});

 

Summary

A basic Express.js app is simple to create. It requires setting up a Node.js project, installing Express, and defining routes for handling requests. Express’s flexibility allows you to easily add features like logging or more complex routing. This minimal setup serves as the foundation for more advanced applications, including APIs and dynamic websites.