Stacked on #33194 and #33200. When Suspense boundaries reveal during streaming, the Fizz runtime will be responsible for animating the reveal if necessary (not in this PR). However, for the future runtime to know what to do it needs to know about the `<ViewTransition>` configuration to apply. Ofc, these are virtual nodes that disappear from the HTML. We could model them as comments like we do with other virtual nodes like Suspense and Activity. However, that doesn't let us target them with querySelector and CSS (for no-JS transitions). We also don't have to model every ViewTransition since not every combination can happen using only the server runtime. So instead this collapses `<ViewTransition>` and applies the configuration to the inner DOM nodes. ```js <ViewTransition name="hi"> <div /> <div /> </ViewTransition> ``` Becomes: ```html <div vt-name="hi" vt-update="auto"></div> <div vt-name="hi_1" vt-update="auto"></div> ``` I use `vt-` prefix as opposed to `data-` to keep these virtual attributes away from user specific ones but we're effectively claiming this namespace. There are four triggers `vt-update`, `vt-enter`, `vt-exit` and `vt-share`. The server resolves which ones might apply to this DOM node. The value represents the class name (after resolving view-transition-type mappings) or `"auto"` if no specific class name is needed but this is still a trigger. The value can also be `"none"`. This is different from missing because for example an `vt-update="none"` will block mutations inside it from triggering the boundary where as a missing `vt-update` would bubble up to be handled by a parent. `vt-name` is technically only necessary when `vt-share` is specified to find a pair. However, since an explicit name can also be used to target specific CSS selectors, we include it even for other cases. We want to exclude as many of these annotations as possible. `vt-enter` can only affect the first DOM node inside a Suspense boundary's content since the reveal would cause it to enter but nothing deeper inside. Similarly `vt-exit` can only affect the first DOM node inside a fallback. So for every other case we can exclude them. (For future MPA ViewTransitions of the whole document it might also be something we annotate to children inside the `<body>` as well.) Ideally we'd only include `vt-enter` for Suspense boundaries that actually flushed a fallback but since we prepare all that content earlier it's hard to know. `vt-share` can be anywhere inside an fallback or content. Technically we don't have to include it outside the root most Suspense boundary or for boundaries that are inlined into the root shell. However, this is tricky to detect. It would also not be correct for future MPA ViewTransitions because in that case the shared scenario can affect anything in the two documents so it needs to be in every node everywhere which is effectively what we do. If a `share` class is specified but it has no explicit name, we can exclude it since it can't match anything. `vt-update` is only necessary if something below or a sibling might update like a Suspense boundary. However, since we don't know when rendering a segment if it'll later asynchronously add a Suspense boundary later we have to assume that anywhere might have a child. So these are always included. We collapse to use the inner most one when directly nested though since that's the one that ends up winning. There are some weird edge cases that can't be fully modeled by the lack of virtual nodes. |
||
|---|---|---|
| .codesandbox | ||
| .github | ||
| compiler | ||
| fixtures | ||
| packages | ||
| scripts | ||
| .editorconfig | ||
| .eslintignore | ||
| .eslintrc.js | ||
| .git-blame-ignore-revs | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .nvmrc | ||
| .prettierignore | ||
| .prettierrc.js | ||
| .watchmanconfig | ||
| babel.config-react-compiler.js | ||
| babel.config-ts.js | ||
| babel.config.js | ||
| CHANGELOG.md | ||
| CODE_OF_CONDUCT.md | ||
| CONTRIBUTING.md | ||
| dangerfile.js | ||
| LICENSE | ||
| MAINTAINERS | ||
| package.json | ||
| react.code-workspace | ||
| ReactVersions.js | ||
| README.md | ||
| SECURITY.md | ||
| yarn.lock | ||
React ·

React is a JavaScript library for building user interfaces.
- Declarative: React makes it painless to create interactive UIs. Design simple views for each state in your application, and React will efficiently update and render just the right components when your data changes. Declarative views make your code more predictable, simpler to understand, and easier to debug.
- Component-Based: Build encapsulated components that manage their own state, then compose them to make complex UIs. Since component logic is written in JavaScript instead of templates, you can easily pass rich data through your app and keep the state out of the DOM.
- Learn Once, Write Anywhere: We don't make assumptions about the rest of your technology stack, so you can develop new features in React without rewriting existing code. React can also render on the server using Node and power mobile apps using React Native.
Learn how to use React in your project.
Installation
React has been designed for gradual adoption from the start, and you can use as little or as much React as you need:
- Use Quick Start to get a taste of React.
- Add React to an Existing Project to use as little or as much React as you need.
- Create a New React App if you're looking for a powerful JavaScript toolchain.
Documentation
You can find the React documentation on the website.
Check out the Getting Started page for a quick overview.
The documentation is divided into several sections:
- Quick Start
- Tutorial
- Thinking in React
- Installation
- Describing the UI
- Adding Interactivity
- Managing State
- Advanced Guides
- API Reference
- Where to Get Support
- Contributing Guide
You can improve it by sending pull requests to this repository.
Examples
We have several examples on the website. Here is the first one to get you started:
import { createRoot } from 'react-dom/client';
function HelloMessage({ name }) {
return <div>Hello {name}</div>;
}
const root = createRoot(document.getElementById('container'));
root.render(<HelloMessage name="Taylor" />);
This example will render "Hello Taylor" into a container on the page.
You'll notice that we used an HTML-like syntax; we call it JSX. JSX is not required to use React, but it makes code more readable, and writing it feels like writing HTML.
Contributing
The main purpose of this repository is to continue evolving React core, making it faster and easier to use. Development of React happens in the open on GitHub, and we are grateful to the community for contributing bugfixes and improvements. Read below to learn how you can take part in improving React.
Code of Conduct
Facebook has adopted a Code of Conduct that we expect project participants to adhere to. Please read the full text so that you can understand what actions will and will not be tolerated.
Contributing Guide
Read our contributing guide to learn about our development process, how to propose bugfixes and improvements, and how to build and test your changes to React.
Good First Issues
To help you get your feet wet and get you familiar with our contribution process, we have a list of good first issues that contain bugs that have a relatively limited scope. This is a great place to get started.
License
React is MIT licensed.