Node.js – Express.js Introduction

Node.js – Express.js Introduction

Express.js is a fast, minimalistic, and flexible web application framework for Node.js. It is designed to simplify the process of building web applications and RESTful APIs by providing powerful features for routing, middleware handling, and server-side logic.

Express is the most popular web framework in the Node.js ecosystem and serves as the backbone for many large-scale web applications.

What is Express.js?

• Built on top of Node.js' http module
• Provides a robust set of features for web and mobile applications
• Great for building single-page, multi-page, or hybrid web applications
• Supports middleware, routing, template engines, request parsing, and more

Why Use Express.js?

• Minimal and unopinionated: you control structure
• Easy to set up and learn
• Supports routing, middleware, static files, and view engines out of the box
• Scalable and production-ready
• Compatible with any front-end framework

Installing Express.js

To install Express.js in your Node.js project:

Basic Express Server Example

Output:

Visit http://localhost:3000 in your browser to see the message.

Defining Routes in Express.js

Using Middleware

Serving Static Files

Now public/style.css is accessible at http://localhost:3000/style.css

Parsing JSON and Form Data

Real-World Use Cases

• Backend for web applications (admin panels, blogs, stores)
• RESTful APIs for mobile and frontend apps
• Microservices architecture
• Authentication and authorization flows
• Integrating with databases (MongoDB, MySQL, PostgreSQL)

Key Takeaways

• Express.js makes building web servers and APIs in Node.js simple and powerful
• Provides built-in support for routing, middleware, views, and static files
• It is scalable, fast, and widely adopted in production-grade applications
• It works seamlessly with third-party libraries, databases, and front-end frameworks