React 17 Documentation Devdocs

Leo Migdal

-Dec 4, 2025, 10:37 AM

The React docs at react.dev provide documentation for the latest version of React. We aim to keep the docs updated within major versions, and do not publish versions for each minor or patch version. When a new major is released, we archive the docs for the previous version as x.react.dev. See our versioning policy for more info. You can find an archive of previous major versions below. 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. For versions older than React 15, see 15.react.dev. This blog site has been archived. Go to react.dev/blog to see the recent posts. Today, we are releasing React 17!

We’ve written at length about the role of the React 17 release and the changes it contains in the React 17 RC blog post. This post is a brief summary of it, so if you’ve already read the RC post, you can skip this one. The React 17 release is unusual because it doesn’t add any new developer-facing features. Instead, this release is primarily focused on making it easier to upgrade React itself. In particular, React 17 is a “stepping stone” release that makes it safer to embed a tree managed by one version of React inside a tree managed by a different version of React. It also makes it easier to embed React into apps built with other technologies.

The library for web and native user interfaces React lets you build user interfaces out of individual pieces called components. Create your own React components like Thumbnail, LikeButton, and Video. Then combine them into entire screens, pages, and apps. Whether you work on your own or with thousands of other developers, using React feels the same. It is designed to let you seamlessly combine components written by independent people, teams, and organizations.

React components are JavaScript functions. Want to show some content conditionally? Use an if statement. Displaying a list? Try array map(). Learning React is learning programming.

This markup syntax is called JSX. It is a JavaScript syntax extension popularized by React. Putting JSX markup close to related rendering logic makes React components easy to create, maintain, and delete. 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. React apps are made out of components.

A component is a piece of the UI (user interface) that has its own logic and appearance. A component can be as small as a button, or as large as an entire page. React components are JavaScript functions that return markup: Now that you’ve declared MyButton, you can nest it into another component: Notice that <MyButton /> starts with a capital letter. That’s how you know it’s a React component.

React component names must always start with a capital letter, while HTML tags must be lowercase. A complete release history for React is available on GitHub.Changelogs for recent releases can also be found below. The current docs are for React 18. For React 17, see https://17.reactjs.org. See our FAQ for information about our versioning policy and commitment to stability. This section provides detailed reference documentation for working with React.

For an introduction to React, please visit the Learn section. The React reference documentation is broken down into functional subsections: React-dom contains features that are only supported for web applications (which run in the browser DOM environment). This section is broken into the following: React has idioms — or rules — for how to express patterns in a way that is easy to understand and yields high-quality applications: There was an error while loading.

Please reload this page. Open https://react.dev/versions Go to previous versions section (https://react.dev/versions#previous-versions) and click on 16.react.dev (https://16.react.dev/). It will redirect to https://17.reactjs.org/ Documentation for React 16 (https://16.react.dev/) is redirecting to React 17 (https://17.reactjs.org/) documentation instead of React 16 documentation. This page is an overview of the React documentation and related resources. React is a JavaScript library for building user interfaces.

Learn what React is all about on our homepage or in the tutorial. React has been designed from the start for gradual adoption, and 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 a simple HTML page, or start a complex React-powered app, the links in this section will help you get started. If you’re interested in playing around with React, you can use an online code playground. Try a Hello World template on CodePen or CodeSandbox. If you prefer to use your own text editor, you can also download this HTML file, edit it, and open it from the local filesystem in your browser.

It does a slow runtime code transformation, so we’d only recommend using this for simple demos.

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React components are JavaScript functions. Want to show some content conditionally? Use an if statement. Displaying a list? Try array map(). Learning React is learning programming.