What is React.js and How Can This Technology Be Used to Create a Custom Web Application?

What is React.js?

The React library was created by Facebook developers in response to a problem they faced. They were looking for a way to build dynamic, interactive, and visually appealing interfaces without sacrificing efficiency and performance. Thus, React.js was born.

Initially intended for internal projects, it was released as open source in 2013 and took the JavaScript community by storm. It is still maintained by Facebook, and now millions of developers and hundreds of contributors work with it.

React.js is an efficient and flexible JavaScript library for building user interfaces. It enables engineers to quickly create complex user interfaces for web and mobile applications. Its approach to building UIs is component-based, meaning the developer creates isolated pieces of code with their own properties and functions, which makes debugging the entire code easier.

This structure guarantees several business advantages. Here are some of them:

• Better performance
• Faster development
• Lower maintenance costs
• Easier onboarding of new developers (thanks to clear code structure)

Beyond the component structure, React's uniqueness lies in two features: the use of JSX and the virtual DOM.

About the Advantages of React.js

Dynamic and Growing Open Source Community

By choosing React.js, you gain access to thousands of passionate React developers who continue to contribute to its evolution. As one of the most popular open-source technologies, it has over 2 million repositories on GitHub. However, React is now considered a mature and stable technology. The community continues to create new frameworks and tools, such as Storybook and React Bootstrap. They also provide support to anyone just starting with React. Plus, it is backed by a giant like Facebook.

It Will Save You Time and Money

There are thousands of reusable components available as open-source libraries. Developers can use them across different projects, working more efficiently without reinventing the wheel. This approach leads to much higher code quality and significantly reduces the time needed to build applications (thus saving developer time and lowering project costs).

Better Performance

React was created to solve the problem of low performance in more complex applications. In short, it worked. Thanks to the virtual DOM and a wealth of features and utilities, it delivers excellent web performance, ensuring blazing-fast applications with low load times.

Great UX and UI

React.js simplifies building dynamic web applications because it guarantees more functionality with less coding, a direct benefit of its component structure. The virtual DOM offers a unique and efficient way to update views in an application by updating only individual components when changes are detected. This enables the creation of advanced applications with interactive user interfaces. The vast majority of components have been pre-coded and placed in the GitHub repository.

One-Way Data Flow

In React.js, how a user sees a component depends on its state. Any user action (e.g., clicking a button or filling a field) can change the component's state. This change is passed to its view and, in turn, to descendant components.

This approach makes the application more efficient (because the relationship between individual interface elements is clearly defined), less error-prone, and easier to debug (since the developer has more control over the data flow). One-way data flow also simplifies performance analysis, as any slowdowns can be detected instantly because changes to a component affect only that component.

SEO-Friendly

As important as it is, not many JavaScript frameworks handle search engine optimization well. React.js significantly improves page load speed, which is one of the main criteria in Google's indexing algorithm. Additionally, React-built applications are lightweight, support server-side rendering, and can load in an instant.

Cross-Platform Development with React Native

React Native is a framework created by Facebook to accelerate the mobile app development process. Previously written React code allows you to build apps for both Android and iOS platforms simultaneously. Because bridges are used to convert JavaScript into native components, the code is used to create native apps for both iOS and Android.

This is ideal if you need to create a simple mobile app that does not require a lot of resources. The more complex the app's features, the more native code snippets need to be written. Code created for a web app can be reused for mobile apps — developers build a reusable library that can be used in both web and mobile applications.

Can You Build a Server-Side Rendered App with React?

First, we need to clarify the main differences between client-side rendering and server-side rendering.

In client-side rendering, the browser loads a basic HTML page, then renders the JavaScript parts and fills them with content. Server-side rendering means React components are rendered directly on the server, outputting HTML content.

By combining them into a web application that can display simultaneously on multiple platforms, we get an isomorphic application that renders both on the server and on the client (web browser). When building such an app, developers construct a single shared component tree that is rendered on the server upon request. As a result, HTML with all data is sent to the browser, which subsequently loads the JavaScript in the client-side version of the React app.

This approach has two main advantages:

• Improved SEO
• Improved performance

Search engines do not read JavaScript. If content is not in HTML, they perceive it as an empty page, no matter how useful it is.

In server-rendered applications, performance depends only on server resources and users' network capabilities. And it has been said many times that improving app speed significantly enhances the overall user experience.

When Should You Use React for Web Development?

React has proven its capabilities in building both custom web applications (just look at Netflix, Instagram, PayPal, and many others) and simple single-page applications (SPAs). The main difference between a single-page application and a traditional multi-page one is that navigation in an SPA does not require moving to a completely new page. Instead, views are loaded within a single page. With proper routing setup, single-page applications run even faster and are better optimized.

Returning to the types of applications you can build with React.js... Well, there are many.

Social Networks

Why does it work so well?

• Great for building single-page applications
• Easy social sharing with server-side rendering
• Simple real-time data handling with Websockets

Examples:

• Facebook
• Instagram
• Pinterest

Video Platforms

Why does it work so well?

• Powerful single-page applications
• Good performance

Examples:

• Netflix
• Sharing economy platforms

Sharing Economy Platforms

Why does it work so well?

• Great for building single-page applications
• Easy social sharing with server-side rendering
• Simple real-time data handling with Websockets

Examples:

• Uber
• Uber Eats
• Airbnb

SaaS Platforms

Why does it work so well?

• Reusable components
• Fast UI updates with the virtual DOM
• Fast page rendering with isomorphic JS

Examples:

• InVision
• Zapier
• Asana

E-commerce Platforms

Why does it work so well?

• Easy component maintenance
• Excellent performance
• Interactive SPAs

Examples:

• Shopify
• Shopping.com

Communication Platforms

Why does it work so well?

• Great for building single-page applications
• Sophisticated real-time data handling with Websockets

Examples:

• WhatsApp
• Discord
• Skype

What Is JSX?

HTML files are the foundation of any basic website. They are read by web browsers and translated to display on devices as web pages with the required