Introduction to Express.js

What is Express?

Express is a web development framework that uses Node.js. Express is a Node.js-based framework for developing single (SPA), multipage (MPA), and hybrid web applications, as well as REST API. Express is built on top of HTTP and connections. Express is built around Ruby's Sinatra framework.

Why use Express?

Express provides the following features:

• Parses arguments and headers.
• It supports routing.
• Supports multiple view engines, including Jade, EJS, and JSHtml.
• Handle configurations.
• Provides support during sessions.
• Enables content negotiation.
• Supports error handling.
• Supports multiple databases.
• RDBMS (MySQL, MS SQL) and NoSQL (MongoDB, Firebase, Redis) are two types of databases.

Core features of Express.js

• Routing: Express.js allows you to define routes that handle various HTTP methods and URLs.​
• Middleware allows for the addition of functionality to the request-response cycle.​
• Templating: Express supports a variety of templating engines, including EJS, Handlebars, and Pug, to render dynamic HTML content.​
• Error Handling: Express includes techniques for handling errors gracefully.​
• Static File Serving: Express supports HTML, CSS, and JavaScript.

Install Express.js in a Node.js

To install Express.js using npm, the Node.js package manager executes the command: npm install express.

Create an Express.js application

To create an Express.js application, you first require the Express module and then run the express() function.

Advantages of Express.js

• Fast and lightweight: Simple design allows for speedy and effective app development.
• Middleware: A powerful middleware framework for modular and organized development.
• Routing: A simple routing system for developing RESTful APIs and managing requests.
• Large Ecosystem: Many plugins and middleware are available for easy enhancement of functionality.
• Flexibility: Enables developers to structure apps based on their choices.

Disadvantages of Express.js

• Minimalistic: In contrast to more opinionated frameworks, it lacks built-in features.
• Learning Curve: A steep learning curve, particularly for those new to JavaScript and asynchronous programming.
• Manual Configuration: Routing, middleware, and other components must be configured manually, which results in boilerplate code and additional development time.
• Security Concerns: Developers are in charge of implementing security features, which might lead to vulnerabilities if not done correctly.
• Performance: Poorly optimized code or middleware can influence application performance, necessitating special attention for high-traffic applications.

Companies Using Express JS

• Uber: The international ride-hailing corporation uses Express.js for its online services and APIs.
• Netflix: The prominent streaming service uses Express.js for some backend technology.
• PayPal: The online payment system uses Express.js to develop some of its web applications and services.
• Medium: Express.js is a backend service used by Medium's online publishing platform.
• LinkedIn: The professional networking site uses Express.js in its technology stack for some functions.
• Walmart: The international retail business employs Express.js in some elements of its online development.
• Trello: Trello, a collaboration application, uses Express.js to develop its backend services.
• NASA: The United States Space Agency has adopted Express.js for some web apps and services.