Getting Started with Express.js for Web Development

Express.js is a simple and flexible framework designed for building web applications and APIs with Node.js. While Node.js is powerful, writing server logic directly with it can be time-consuming and repetitive. Express.js simplifies the process by offering a structured approach with ready-to-use tools for routing, managing middleware, and handling user requests.

Key Features of Express.js

Express.js comes with several features that make it a favorite for building web applications and APIs. Here are some of the key features:

1. Middleware

Middleware functions act as intermediaries in the request-response cycle. They help you process incoming requests before sending a response, such as checking user authentication, logging, or handling errors. Middleware makes your application modular and easier to manage by breaking functionality into smaller, reusable parts.

2. Routing

Routing in Express.js allows you to define how the server should respond to requests based on the URL and HTTP methods (like GET, POST, or DELETE). It provides a simple way to organize and manage application endpoints, ensuring users or APIs receive the correct responses.

3. View System

Express.js includes a robust view system that works with templating engines like EJS, Pug, or Handlebars. This feature enables you to create dynamic, reusable templates for rendering HTML pages. Views help separate application logic from presentation logic, which is useful for creating user-friendly, server-rendered applications.

4. Templates

Templates are a specific part of the view system that allows developers to generate HTML based on data dynamically. With templating engines, you can create reusable components and inject data into them, making it easy to render personalized content like user profiles, dashboards, or search results.

Setup: Installing and Creating a Basic Server

Let's get started with Express.js:

Install Node.js: Download and install Node.js from the official website.

Initialize a Project: Open your terminal and run the following commands:
mkdir my-express-app
cd my-express-app
npm init -y

Install Express: Add Express to your project with this command:
npm install express

Creating a simple server with Hello World

Create a file named server.js in your my-express-app directory

// Import Express
const express = require('express'); 

// Create an Express app
const app = express();

// Define a route for the homepage
app.get('/', (req, res) => {
  res.send('Hello, World!');
});

// Start the server on port 3000
app.listen(3000, () => {
  console.log('Server is running on http://localhost:3000');
});

Save this code in the server.js file.

Run the server using the following command:
node server.js

Open your browser and go to http://localhost:3000.
You’ll see "Hello, World!" displayed!.

Running in Development

During development, you might want to automatically restart your server whenever you make changes to your code. You can use nodemon for this.
To install nodemon, run:
npm install --save-dev nodemon

Then, modify your package.json file to add a start script:

"scripts": {
  "start": "nodemon server.js"
}

Now, you can start the server in development mode with:
npm start

Conclusion

Express.js is an excellent choice for both beginners and experienced developers who want to build web applications or APIs quickly. Its simplicity, combined with powerful features like routing, middleware, view systems, and templates, helps you write clean and efficient code. As you get comfortable with the basics, you can easily explore more advanced features to build robust applications. With strong community support, extensive documentation, and an active ecosystem, Express.js is a reliable framework that makes development faster, more flexible, and more enjoyable.