Introduction to Express.js Framework

These days, there are dozens of incredible tools for building robust web applications with complex functionalities. Having so many options can make deciding which is best for you difficult. However, when it comes to Back End Development, the answer is often a no-brainer. Express.js is one of the most powerful and popular Backend solutions. GitHub features it as the most popular Node.js framework, describing it as fast, flexible, and minimalist. It's not surprising that it's one of the pillars of one of the most loved and cutting-edge software stacks for Web Development, the MERN Stack. You should consider Express.js as your go-to web application framework for many reasons. In this manner, we've covered all the most important aspects of it. 

What is Express.js? 

As mentioned before, Express.js is a high-performant, minimalist Node.js framework, created by TJ Holowaychuk. Compared to other Backend development tools, Express.js is very easy to learn and work with, provided you know the basics of JavaScript. No wonder why it is such a popular choice in the Node.js community. It has a reputation for being the standard server framework for Node.js. experts describe it as a "minimalist web framework" because it doesn't overwhelm you with many unnecessary packages. 

You may also hear the word "unopinionated," which basically means that it doesn't dictate how you should build your app. In other words, there's no "right way" to do things. This gives developers more flexibility and control, helping streamline the Product Development Life Cycle (PDLC). Despite its minimalist design, it gives you a wide range of tools for robust routing, error handling, database drivers, and middleware functions. In case you didn't know, middleware is basically a request handler that helps you keep track of the app's request-response cycle. 

That's why it's perfect for server-side applications and database integrations. On the other hand, its template engines help Backend developers create dynamic content on the server. On top of that, Express.js has built-in core features for content negotiation and security and uses Node.js's non-blocking I/O model with event-driven architecture. It is great for handling input and output operations, including reading files or sending data over the Internet. Plus, it is based on the most popular language on the planet, JavaScript, allowing you to use TypeScript for enhanced collaboration. All these reasons make it ideal for building RESTful APIs and Microservices. As you can see, Express.js can help you build almost any app, including FinTech, eCommerce, and hybrid web applications. 

How to Start with Express.js? 

Not only is Express.js easy to learn, but it is also easy to get started with. Since it's a Node.js framework, you need to have Node.js installed in your development environment along with npm. It's worth noting that you should ideally understand the basic aspects of JavaScript before jumping into Express.js. That includes variables, objects, properties, functions, methods, arrays, loops, conditionals, promises, and callbacks. It will be much easier for you if you're familiar with advanced JavaScript concepts. You can easily start using npm to initialize a new npm project by running the npm init command in your project directory. The next step is to install Express.js as a dependency by running npm install express. 

Then, you have to create an Express.js server by writing the following code in a server.js file: "const express = require('express');" The express module works as a function you can then run in the following line by creating an app variable: "const app = express();" Luckily, Express.js gives you intuitive functions for defining route handlers for different HTTP methods and paths or URL patterns. It looks like this: “app.get(..), app.post(...), and app.put(...)” These functions take one parameter that targets a URL and another that involves the server's request method (req) and the response object (res) it gives to the client requests. Here's an oversimplified example of a code snippet handling the application's request-response cycle. 

After you've done that, you can start the server with the "listen" function. It requires you to pass at least one parameter representing the port number that will listen to incoming requests or connections. Note that if you don't select a request object, your Operating System (OS) will choose one randomly. You can select three more parameters: host, backlog, and callback functions. Here's a simple example that includes all the previous code and starts the server with the listen function. 

Why Use Express.j?

Some people new to Web Development often overlook that Node.js is just a JavaScript runtime environment. Server-side Development with vanilla Node.js is technically possible, but it can be fairly hard and time-consuming. That's why most businesses, including large corporations, opt to use a framework that simplifies things. Express.js makes building web applications and Node.js Application Programming Interfaces (APIs) much easier and faster. The best thing is that it still gives you the flexibility and control to customize it. Being part of the top four most popular frameworks, Express.js has a massive community of developers. 

That translates to having top-notch support, guidance, and learning sources for learning and mastering Express.js. It's also worth noting that it has been around for quite some time as an open-source software, making it a mature and reputable tool. Compared to other Node.js frameworks for Backend Development like Nest.js, Express.js has a low learning curve. Its simplicity and flexibility provide a smooth developer experience, helping avoid problems like over-engineering. 

Moreover, Express.js gives you an easy way to handle HTML and other static files and send them to the browser. Debugging is also much simpler. Moreover, the latest version has amazing additional features like HTML helpers and middleware modules. It's based on JavaScript, the most popular programming language for Front-End Development. As a result, it is possible to build a complete and world-class web app using a single language. 

Conclusion

Regarding Backend Development for scalable, fast, high-performing web apps, Express.js checks all the boxes. It's hard for me to think of project requirements for which Express.js isn't an excellent choice in Backend Development. A robust set of tools for handling HTTP methods, simple routing, application structure, debugging, built-in middleware functions, error handling, deployment, and API development. They are the building blocks of any successful web app. Knowing that it has a massive active community and a mature ecosystem, you can confidently choose it for your project. Whether it is for basic or complex web applications, Express.js can help a lot in developing advanced functions.

Furthermore, you can combine it with cutting-edge technologies like tRPC and gRPC to improve the developer experience and performance. It's worth noting that despite its popularity in web application development, Express.js also gives you the tools to develop mobile applications. It's clear why some people view it as the perfect framework. Yet, you may want to look into React Native or Flutter if you are interested in mobile development. As a UX-driven digital agency covering all the PDLC stages, we strongly support Express.js for the rapid development of server-side web applications.