Express.js - Everything You Need to Know

Express.js is a back-end web app framework. It was released on 16 November 2020. Tj Holoway(developer), Strong Loop (American company), and some other companies contributed to its creation. Now, like any other framework, there are some prerequisites of Express.js: npm and Node.js must be installed in your system.

Further, some developers use Express.js to create robust and scalable web apps. Whereas others use Express.js because of its flexibility, ease of use, and powerful features. Their latest version is 4.18.2. Version 5.0.0 is still in the beta phase.

Let's look at the key features of Express.js:

1. It is one of the most minimal and lightweight web frameworks.
2. Support for middleware is also provided in Express.js.
3. Express.js has a powerful routing system. Due to these very reasons, developers find it easy to handle varying HTTP requests for a variety of URLs in Express.js.
4. Rendering dynamic HTML pages is also easy in Express.js. That's because Express.js has a lot of template engines.
5. The best thing about Express.js is its support for databases. You can use Node.js database modules as well as other databases like MongoDB and MySQL.
6. Express.js can handle concurrent requests. In fact, it can handle up to 15,000 requests per second. Now, how can Express.js handle such a large number of concurrent connections? Well, this is because Express.js uses an event-driven, non-blocking I/O model. That's how Express.js is able to handle multiple requests at one time.
7. Developers can also easily scale their apps because of the clustering support given in Express.js.
8. There's a default error handler in Express.js that processes and finds errors. There are also features like Helmet that protect Express.js against cross-site scripting and cross-site request forgery.

But still, why should you learn it?

Well, since it's designed on top of Node.js if you have the know-how of Node.js, definitely learn it. It will be easy for you to master Express.js.And since it has a lot of features and middleware support, it's comparatively quick to develop web apps in Express.js. Developers can also customize apps however they want in Express.js. But there's a catch - flexibility can backfire at times! There are different libraries as well to help you in this case.

But alas, like any other framework, Express.js also has some cons. For instance, there's no structure using which you can organize your code. Because of this, code can turn messy and difficult to maintain. And since Express.js is built on top of Node.js, there is overhead in Express.js. Overhead will increase if one has to build a high-performing app. It is also lacking when it comes to some advanced features.