React (software)

React (also known as React.js or ReactJS) is a free and open-source front-end JavaScript library that aims to make building user interfaces based on components more "seamless". It is maintained by a community of individual developers and companies and governed by the React Foundation, an independent foundation hosted by the Linux Foundation. According to the 2025 Stack Overflow Developer Survey, React is one of the most commonly used web technologies. React can be used to develop single-page, mobile, or server-rendered applications with frameworks like Next.js and React Router. Because React is only concerned with the user interface and rendering components to the DOM, React applications often rely on libraries for routing and other client-side functionality. A key advantage of React is that it only re-renders those parts of the page that have changed, avoiding unnecessary re-rendering of unchanged DOM elements. React is used by an estimated 6.1% of all websites.

React (also known as React.js or ReactJS) is a free and open-source front-end JavaScript library that aims to make building user interfaces based on components more "seamless". It is maintained by a community of individual developers and companies and governed by the React Foundation, an independent foundation hosted by the Linux Foundation. According to the 2025 Stack Overflow Developer Survey, React is one of the most commonly used web technologies. React can be used to develop single-page, mobile, or server-rendered applications with frameworks like Next.js and React Router. Because React is only concerned with the user interface and rendering components to the DOM, React applications often rely on libraries for routing and other client-side functionality. A key advantage of React is that it only re-renders those parts of the page that have changed, avoiding unnecessary re-rendering of unchanged DOM elements. React is used by an estimated 6.1% of all websites. async function MyComponent() { const message = await fetchMessageFromDb(); return ( Message: {message} ); } React Server Components became stable in React 19. They can render ahead of time in an environment separate from the client application, either at build time or on a web server for each request. Server Components can access server-side data sources and pass data and JSX to Client Components. React also supports Server Functions, which allow Client Components to call asynchronous functions executed on the server. Server Functions can be marked with the "use server" directive and can be defined in Server Components or imported into Client Components. class ParentComponent extends React.Component { state = { color: 'green' }; render() { return ( ); } } Class components are still supported, but React recommends defining new components as functions instead of classes. function Example() { // Declare a new state variable, which we'll call "count" const [count, setCount] = useState(0); return ( You clicked {count} times setCount(count + 1)}> Click me ); }

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