React is the library for web and native user interfaces. Build user interfaces out of individual pieces called components written in JavaScript. React is designed to let you seamlessly …

Quick Start Welcome to the React documentation! This page will give you an introduction to 80% of the React concepts that you will use on a daily basis.

You can use as little or as much React as you need. Whether you want to get a taste of React, add some interactivity to an HTML page, or start a complex React-powered app, this section …

In 2023, we launched our new docs for React 18 as react.dev. The legacy React 18 docs are available at legacy.reactjs.org. Versions 17 and below are hosted on legacy sites.

If your app has constraints not well-served by existing frameworks, you prefer to build your own framework, or you just want to learn the basics of a React app, you can build a React app from …

If you want to build your own solutions, see our guide to build a React app from Scratch for instructions on how to set up a new React project starting with a build tool like Vite, Parcel, or …

Instead of using an empty HTML file and letting React “take over” managing the page with JavaScript, they also generate the HTML automatically from your React components.

如果你想构建自己的解决方案，请参阅我们的 从零构建一个 React 应用 指南，该指南提供了如何使用 Vite， Parcel，或 RSbuild 等构建工具设置新 React 项目的说明。

Components and Hooks must be pure – Purity makes your code easier to understand, debug, and allows React to automatically optimize your components and hooks correctly.

Conditional Rendering Your components will often need to display different things depending on different conditions. In React, you can conditionally render JSX using JavaScript syntax like if …