What is React.js? Uses, Examples, & More

In this guide, we'll unravel its core concepts, unlock powerful tools, and show you how it can elevate your next project.

React.JS History

• Current version of React.JS: is V18.0.0 today at (2/24)
• Public release: July 2013, version 0.3.0.
• First internal use: 2011, for Facebook's News Feed.
• Creator: Facebook Software Engineer, Jordan Walke, created it.

What does React.JS do?

Typically, when you access a webpage by entering its URL into your browser, a request is sent to the server, and the browser renders the webpage. Subsequent requests for new pages or resources on the same website also trigger server requests, leading to a back-and-forth loading process between the client (your browser) and the server. While this traditional method works adequately for most websites, it can be inefficient for highly data-driven sites, resulting in a less than optimal user experience.

Moreover, in traditional JavaScript applications, updating data requires manual manipulation of the Document Object Model (DOM) to reflect these changes. This involves identifying the changed data and updating the DOM accordingly, often necessitating a full page reload.

React adopts a different approach by enabling the development of single-page applications (SPAs). SPAs initially load a single HTML document upon the first request and subsequently update specific sections or content of the webpage using JavaScript, rather than reloading the entire page for each new request.

This approach, known as client-side routing, allows React to intercept requests and fetch only the necessary sections, minimizing the need for full page reloads. Consequently, SPAs built with React offer improved performance and a more dynamic user experience.

React leverages a virtual DOM, which is a representation of the actual DOM. Whenever there's a change in the data state, React immediately updates the virtual DOM to reflect this change. It then compares the virtual DOM to the actual DOM to identify the differences.

React determines the most efficient way to update the actual DOM based on these differences, optimizing performance by only rendering the necessary changes. This results in rapid updates to React components and UIs without the need for full page reloads, enhancing the overall user experience.

Key React.JS concepts

React distinguishes itself from other JavaScript frameworks with several unique concepts that set it apart both historically and in comparison to more recent frameworks.

Components

In React, applications are constructed using components, which are individual units of the user interface that possess their own logic and visual representation. Components can range in size from small elements like buttons to entire pages.

These components in React are essentially JavaScript functions that generate markup.

MyButton component is created. Now it's ready to be wrapped inside App Component

Notice that <MyButton /> starts with a capital letter. That’s how you know it’s a React component. Think of React components like proper nouns - they get a capital letter at the beginning, just like your name! HTML tags are more like everyday words, so they stay lowercase.

Writing markup with JSX

The syntax used above for markup is known as JSX in React. While JSX is not mandatory, it's widely adopted in most React projects due to its convenience. The primary tools recommended for local development seamlessly support JSX.

Compared to HTML, JSX imposes stricter rules. For instance, You have to close tags like <br />. Components in React can only return one single element. You have to wrap them into a shared parent, like a <div>...</div> or an empty <>...</> wrapper

Need to move a bunch of HTML into JSX? Online converters can help!

Props and State

Managing state in JavaScript web applications can be challenging, especially when it involves tracking user interactions such as button clicks or selected options in a list. React addresses this complexity by implementing a one-way data flow.

where parent components pass data down to their child components through properties, known as props. When the data within a parent component changes, React efficiently updates the child components that rely on that data. However, child components cannot directly alter the data received from their parent; instead, they communicate with the parent component through callbacks or functions passed as props. This approach streamlines debugging, enhances code maintainability, and optimizes performance by allowing React to efficiently render components.

For instance, in the example provided, if we needed to customize the button text and add class to a button of a Button component, we could achieve this using props.

Lifecycle Methods

React's component lifecycle functions, event handlers, and custom hooks provide various opportunities to execute code at precise moments during state updates, data changes, and user interactions. This is where lifecycle methods come in. Lifecycle methods are special functions that allow developers to hook into different stages of a component's life cycle. These methods provide opportunities to execute code at specific moments during the component's existence, such as when it is created, updated, or removed from the DOM.

The componentDidMount lifecycle method serves as the entry point for actions after a component integrates into the DOM. This is where data fetching, DOM manipulation, and other initialization tasks typically occur.

While lifecycle methods were good in their time, React Hooks offer a modern approach to dealing with side effects like data fetching or DOM manipulation. They're more flexible and "declarative," meaning you can write what you want to achieve instead of following rigid method names. Think of them as a Swiss Army knife for side effects within your components!

React Ecosystem

In addition to all of the features React provides out of the box, because it’s such a popular library, other libraries have been created around it to fill some of React’s gaps. Two prime examples of these sorts of add-on libraries are Redux and React Native.

Redux

React’s one-way data flow is very useful for managing data and state within an application, but there are some cases where that’s not what you need. Redux addresses several of the shortcomings of React’s state management by providing a single, centralized store that holds the entire application state. As your application grows in size and complexity, with many components sharing data and interacting, using Hooks becomes increasingly advantageous.

In comparison to React’s out of the box state management, Redux gives developer teams a bit more structure when it comes to managing state, making it easier for multiple developers to collaborate on the same codebase. It also provides easy debugging with time-traveling, which means you can inspect and replay past actions and state changes to understand how the application arrived at a certain state.

React Native

Released only a couple years after React’s public release, React Native is a toolkit that allows developers who are comfortable building React applications to compile those applications into native mobile apps for iOS and Android. This means that, instead of having to maintain an entirely separate mobile codebase in a different language (Java for Android and Swift for iOS), you can re-use your React components that you have built for the web, while still getting the performance gains of a native mobile application. This approach enables utilization of exclusive mobile-specific functionalities unavailable in traditional web apps, granting you advanced control over the native capabilities of the device.

While Instagram paved the way with React Native, the framework has soared beyond Meta's walls, attracting diverse popular brands to build their mobile experiences.

Benefits of Using React:

• Improved performance: Virtual DOM, declarative style, and efficient rendering contribute to a faster and more responsive user experience.
• Better developer experience: Component-based approach, JSX, and a rich ecosystem lead to a more pleasant and productive development environment.
• Code maintainability: Modular components and clear separation of concerns promote easier maintainability and extensibility.
• Scalability: Ability to handle complex, large-scale applications effectively.
• SEO-friendliness: Can be used to create search-engine-optimized web applications.

Conclusion

Throughout this guide, we've explored the depths of Reactjs, delving into its history, core concepts, and advantages. It's clear that React offers a unique and powerful approach to web development, empowering you to build dynamic, interactive, and performant applications.

From its virtual DOM to its component-based architecture, React streamlines and optimizes development. Forget about full-page reloads and clunky DOM manipulation – React's efficient rendering ensures a smooth and responsive user experience. Coupled with the flexibility of JSX and the vast ecosystem of tools and libraries, React empowers you to craft complex applications with ease.

But React's impact extends beyond technical benefits. Its clear separation of concerns and modularity contribute to cleaner, more maintainable codebases, enhancing collaboration and long-term project health. Whether you're a seasoned developer or just starting your journey, React offers a rewarding and productive development experience.

Are you ready to take the plunge and leverage the power of React in your next project? The resources and knowledge you've gained here provide a solid foundation. Remember, the React community is vibrant and supportive, offering extensive documentation, tutorials, and forums to help you on your way.

So, don't wait! Embrace the React revolution and unlock the potential for exceptional web experiences.