What is Express.js in NodeJS? And How to Install Express.js

Express.js in NodeJS

With its extensive feature set for developing online apps and APIs, Express.js is a simple and adaptable Node.js web application framework. Its foundation is middleware composition, a notion that came from the Ruby development community. Each middleware can carry out the required tasks before handing over control to the next, meaning that an object’s request and response are processed by a sequence of functions as they flow through.

Node.js is a cross-platform and JavaScript runtime environment that allows JavaScript code to be executed outside of a browser. The V8 JavaScript engine from Google, which turns JavaScript into machine code, is used. Express.js makes the process of creating servers much simpler than Node.js, which offers essential modules like http.

Express.js provides developers with a number of functionalities, such as:

1. Easy routing system: For various URL paths and HTTP methods (such as GET, POST, PUT, and DELETE), it simplifies the process of defining routes.
2. Compatibility with templating systems: For dynamic HTML page rendering, Express can interface with a number of templating engines, including EJS, Moustache, Handlebars, Pug (previously Jade), and others.
3. Middleware framework: Built on middleware functions, its architecture allows for extendable and modular application logic for tasks like error handling, authentication, and logging.

Why Express is Popular?

The popularity of Express.js has grown significantly for a number of strong reasons:

• Speed and Simplicity: Express is praised for its speed and ease of use. The main factor in its broad popularity has been its minimalist approach, which concentrates on the essential functions required for a server. Besides being lightweight, it is fast.
• Scalability: Events-driven, non-blocking I/O is used by Node.js and, consequently, Express. Because of this, it can effectively manage many requests at once without buffering data, which makes it extremely scalable for real-time applications that require a lot of data.
• Ease of Learning: Because Express lets developers write both client-side and server-side code in the same language, it’s particularly straightforward for JavaScript developers to learn.
• Dominance in Backend Development: In the realm of backend development, Express.js is the most popular framework. For their production environments, big businesses like Netflix, Uber, and Walmart have embraced it.
• Huge Ecosystem (npm): Node.js boasts the world’s largest ecosystem of libraries, which are overseen by npm (Node Package Manager). Developers may concentrate on application-specific logic because of this extensive library of pre-built modules, which eliminates the need to reinvent the wheel for routine activities.
• Facilitates Team Collaboration: Structures such as Express aid in preserving code standards, which is essential when several team members are working on the same codebase.
• Performance: The V8 engine, developed by Google and written in C++, is the foundation of Node.js and is renowned for its speed. This helps explain why Express apps run so well.

Installing Express.js

Using the default package manager for Node.js, npm, to install Express.js into your project is a simple process.

1. Initialize your project (Optional but Recommended): It’s a good idea to start your project with npm init before adding packages. This command guides you through the creation of a package.json file, which specifies the dependencies and contains metadata about your project. For a faster setup, you can use npm init -yes, which accepts default values.
2. To run npm init -yes in your terminal, follow this example:
3. A package will be package.json file like this (the output might change a little depending on the defaults and npm version):
4. This file serves as a project manifest, and when you install new packages, the dependencies section will be updated automatically.
5. Install Express.js: Once your project is set up, you can install Express using the npm install command. The --save flag (or its shorthand -S) is typically used to ensure the package is added to your project’s dependencies list in package.json.
6. Enter the following command in the root directory of your project:
7. or abbreviation:
8. This command will download the Express package and all its dependencies to your current directory’s node_modules folder. Usually, the only output you’ll get is success messages and maybe a few cautions, but it means the installation is finished.
9. Build a simple Express “Hello World” server: To get a basic Express server up and running, create a JavaScript file (such as app.js or server.js) and add the following code after installation.
10. Save the following code in the app.js file:
11. Start the Express server: Go to the directory where app.js is stored in your terminal, open it, and use the node command to launch the file.
12. Output showing that the server has started and is listening on the designated port will appear:
13. This process will continue to run until you actively terminate it, for example, by using Ctrl + C in the terminal.
14. Open your browser and navigate to the server: Launch your preferred web browser (such as Chrome) and go to either http://localhost:3000 or http://127.0.0.1:3000. In your browser, “Hello, Express World!” ought to appear.

Essentially, installing an Express server is similar to building a custom car from a sturdy chassis (Express.js) and a high-performance engine (Node.js), complete with all the tools (middleware, routing, and templating) needed to deliver passengers (web pages/APIs) to their destinations in a timely and effective manner.