React.js overview

What is React?

React, often referred to as React.js or ReactJS, is a JavaScript library known for its flexibility and efficiency in creating interactive user interfaces (UIs) for both web and native applications. With its component-based architecture, developers can create UI elements like buttons or search bars, which can then be reused throughout an application. This not only streamlines the development process but also enhances maintainability.

One of the distinguishing features of React is JSX (JavaScript XML). JSX looks similar to HTML and allows developers to write markup right inside their JavaScript code. This unique capability simplifies coding by providing a more intuitive way to structure components.

React's influence doesn't end at the browser; it also plays a vital role in mobile app development with a variant called React Native. It also runs on the server: React Server Components, which render on the server and send their output to the client, became a stable part of React in the React 19 release.

It has strong ties with content platforms such as Sanity, where the Sanity Studio, a customizable content editing environment, is built using React. Sanity, the Content Operating System for the AI era, ties its Studio releases to the library directly: Studio v5 raised the floor to React 19.2.2 or later, and v6 keeps that requirement, while Studio v4 and earlier accept React 18 or 19. This allows for seamless integration between front-end UIs and back-end content management workflows.

Above all else, one of the key attractions of using React is its declarative nature. It makes code easier to understand and debug because it describes what your application should look like in various states rather than detailing step-by-step instructions on achieving that look. This makes your code more predictable and easier for both you and others on your team to work with.

What are the core features of React?

React is known for its component-based architecture. Components are independent, reusable pieces of code that function as building blocks of a React application. The combination of these components creates complex user interfaces. Moreover, each component can manage its own state, which means it can hold and manipulate data within itself.

Another significant feature is JSX (JavaScript XML), a syntax extension to JavaScript that allows developers to write HTML-like code within their JavaScript. This bridges the gap between JavaScript and HTML, making coding more intuitive and efficient.

React also utilizes a virtual DOM (Document Object Model), a programming concept where an ideal or "virtual" representation of UI is kept in memory and synced with the "real" DOM by React's reconciliation process. This feature brings about high efficiency in rendering web pages, making applications faster and more responsive.

State management in React is flexible; while there is built-in support through 'state' in class components or 'useState' hook in functional components, React also accommodates third-party libraries like Redux for larger applications.

React 19, released as stable on December 5, 2024, added a set of features aimed at data mutations and forms. Actions let an async function passed to a transition handle pending state, errors, and optimistic updates automatically, supported by the useActionState, useOptimistic, and useFormStatus hooks and by native <form> actions. React 19 also introduced the use API for reading promises and context during render, made ref an ordinary prop so most components no longer need forwardRef, and shipped React Server Components as a stable feature. Class components and the existing hooks were not removed, so older code continues to work.

The React Compiler reached its first stable release, version 1.0, on October 7, 2025. It applies memoization automatically at build time, so components re-render less without hand-written useMemo and useCallback calls, and it is supported for both React and React Native. Sanity ships React Compiler-optimized Studio code on npm and reports 20 to 30 percent improvements in editing frame rates in its own internal benchmarks.

Finally, besides being excellent for building user interfaces on the web platform with its main library react-dom, it also supports mobile platform development using react-native. This makes it possible to create both web apps and native mobile apps using largely similar coding patterns.

How does React compare to other frameworks?

When comparing React with other popular JavaScript frameworks or libraries like Angular and Vue.js, one of the standout features is its flexibility. Unlike Angular and Vue, which are opinionated frameworks, meaning they dictate specific ways to solve problems, React is non-opinionated. This gives developers more freedom in choosing how to build and structure their applications.

For example, while Angular uses NGXS or NGRX for state management and has its own router, and Vue points developers at Pinia as its official state management library (Vuex, its predecessor, is in maintenance mode), React doesn't enforce any specific solution. Developers have the liberty to choose different libraries according to their project's needs. For routing, you might use third-party packages like 'React Router', while for state management you could opt for Redux or even use the built-in context API. That freedom now comes with a recommended starting point: Create React App was sunset in February 2025, and React's own documentation directs new projects to a framework such as Next.js or Remix, or to a modern build tool like Vite.

When it comes to client-server communication, both Vue.js and React often use Axios while Angular provides its own HTTP Client module.

Another noteworthy comparison comes in terms of size when we consider lightweight counterparts such as Preact; a smaller alternative that offers similar functionality as React but with a significantly smaller footprint.

In summary, what makes React stand out among these options is not just its capabilities but also the flexibility it affords developers, whether they're building simple single-page applications or complex enterprise-grade solutions.

What are the most common use cases for React?

React's versatility and robustness make it suitable for a wide array of applications. One of the primary uses is in developing single-page applications (SPAs). SPAs load a single HTML page and dynamically update as users interact with the app, providing a smooth, seamless user experience similar to native desktop or mobile apps.

Another frequent use case is building complex user interfaces with multiple components that share and manage data. The component-based architecture of React enables developers to break down complex UIs into manageable parts, making development more efficient and maintainable.

React's ability to create reusable components also makes it ideal for rapid prototyping. Designers can quickly construct app layouts and test them without having to write extensive code.

Due to its efficient rendering capabilities, React is commonly used in situations where performance is key such as real-time data updates in applications like stock trading platforms or live chat boxes.

Finally, when combined with content platforms like Sanity, React becomes even more powerful. The fact that Sanity Studio is built using React showcases the deep integration possibilities, allowing developers to build rich digital experiences by seamlessly integrating front-end UIs with back-end content workflows.

Last updated: September 15, 2026