What Is React?

We know by now that at the very least, React is a popular JavaScript library for building user interfaces. It's also especially for single-page applications (SPAs). It was created and is maintained by Facebook (now Meta), and has grown into one of the most widely used libraries for front-end development. At its core, React helps developers create dynamic and interactive user interfaces with less effort and better performance.

Unlike traditional methods of updating the user interface directly via the DOM, React adopts a declarative approach. Developers describe what the UI should look like at any given state, and React takes care of updating the actual DOM to match. This eliminates the need for manually writing complicated DOM manipulation logic, making code easier to write and maintain.

React ecosystem

The React ecosystem includes tools and libraries that complement its functionality. Let’s explore some key members of this ecosystem:

• React Router: It enables navigation between pages in a React application. For example, in a blogging platform, React Router can enable navigation between pages like the home page, individual blog posts, and an about page.

• Redux: It helps manage complex application state. Imagine a shopping cart application where we need to track items added to the cart, user details, and payment status across various components. Redux ensures all components have access to the required data without creating a tangled web of dependencies.

• Next.js: A framework built on React for server-side rendering and static site generation. For instance, an e-commerce website using Next.js can serve pre-rendered product pages to users, reducing load times and improving search engine rankings.

• React Native: It extends React's capabilities to mobile app development. For example, a travel booking app built with React Native can provide a seamless user experience on both iOS and Android without requiring separate codebases for each platform.

• MERN stack: The MERN stack integrates React with JavaScript-based technologies and MongoDB to enable full-stack development. For example, a task management app built with the MERN stack can use React for the user interface, Express.js for backend logic, Node.js to run the server, and MongoDB to store tasks and user data.

This ecosystem has made React the go-to choice for modern web development, from creating simple websites to building complex applications used by millions of users.

Why React is popular

React has become immensely popular for several reasons. Let’s explore two of its standout features: the declarative UI approach and its component-based architecture.

Declarative UI: Simplifying user interface updates

Traditional web development often involves imperative programming, where developers explicitly define every step needed to update the DOM. This can quickly become error-prone and difficult to manage as the application grows.

React, on the other hand, adopts a declarative approach. We describe the desired UI for a specific state, and React efficiently updates the DOM to match it. For example, if a user interacts with a button that changes some data, React ensures the UI reflects the updated state without us having to write tedious DOM manipulation code.

Component-based architecture: Building reusable, modular code

In React, everything revolves around components. Components are the building blocks of React applications. They are self-contained units of code that define a piece of the UI and its behavior. For example, a button, a navigation bar, or a user profile card can each be a component.

Components promote reusability and modularity:

• Reusability: Components can be reused across different parts of an application, saving time and reducing code duplication.

• Modularity: Applications are divided into smaller, manageable pieces, making it easier to develop, debug, and maintain.

Let’s look at this way: Imagine we’re assembling a car. Instead of building it from scratch every time, we use pre-made parts like the engine, wheels, and seats. Similarly, React allows us to “assemble” our application using components.

Example: A simple React component

An example component in React:

When this component is rendered in a React application, it displays the Welcome to React! heading.

React’s declarative approach and component-based architecture simplify UI development a lot. It's easier to create dynamic and interactive applications while keeping the codebase organized and maintainable, and React helps us do that.

Now that you understand what React is and why it’s so popular, let's get some hands-on experience with it.