A declarative, efficient, and flexible JavaScript library for building user interfaces. reactjs.org
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[DevTools] Disconnect and Reconnect children of Suspense boundaries instead of Unmounting and Mounting (#34089)
Stacked on #34082.

This keeps the DevToolsInstance children alive inside Offscreen trees
while they're hidden. However, they're sent as unmounted to the front
end store.

This allows DevTools state to be preserved between these two states.

Such as it keeps the "suspended by" set on the SuspenseNode alive since
the children are still mounted. So now you when you resuspend, you can
see what in the children was suspended. This is useful when you're
simulating a suspense but can also be a bit misleading when something
suspended for real since it'll only show the previous suspended set and
not what is currently suspending it since that hasn't committed yet.

SuspenseNodes inside resuspended trees are now kept alive too. That way
they can contribute to the timeline even when resuspended. We can choose
whether to keep them visible in the rects while hidden or not.

In the future we'll also need to add more special cases around Activity.
Because right now if SuspenseNodes are kept alive in the Suspense tab UI
while hidden, then they're also alive inside Activity that are hidden
which maybe we don't want. Maybe simplest would be that they both
disappear from the Suspense tab UI but can be considered for the
timeline.

Another case is that when Activity goes hidden, Fiber will no longer
cause its content to suspend the parent but that's not modeled here. So
hidden Activity will show up as "suspended by" in a parent Suspense.
When they disconnect, they should really be removed from the "suspended
by" set of the parent (and perhaps be shown only on the Activity
boundary itself).
2025-08-06 11:05:19 -04:00
.codesandbox Build react-server-dom-webpack for codesandbox (#32990) 2025-04-22 22:20:21 +02:00
.github Allow runtime_build_and_test action to trigger manually (#33796) 2025-07-16 12:41:35 -04:00
compiler [compiler] Delete PropagatePhiTypes (#34107) 2025-08-04 15:15:51 -07:00
fixtures [Flight] Ignore async stack frames when determining if a Promise was created from user space (#33739) 2025-07-09 09:08:09 -04:00
packages [DevTools] Disconnect and Reconnect children of Suspense boundaries instead of Unmounting and Mounting (#34089) 2025-08-06 11:05:19 -04:00
scripts [Flight] Switch to __turbopack_load_by_url__ (#33791) 2025-07-15 16:55:31 +02:00
.editorconfig Remove trim_trailing_whitespace from editorconfig (#31413) 2024-11-04 15:30:02 -05:00
.eslintignore Fix ESLint and Prettier configs for React Compiler (#29073) 2024-05-15 14:02:57 -07:00
.eslintrc.js [DevTools] More robust resize handling (#34036) 2025-07-29 17:45:00 +02:00
.git-blame-ignore-revs Add run prettier commit to .git-blame-ignore-revs 2024-07-18 17:42:45 -04:00
.gitattributes .gitattributes to ensure LF line endings when we should 2014-01-17 16:25:53 -08:00
.gitignore [forgive] Init (#31918) 2025-02-25 12:19:11 -05:00
.mailmap updates mailmap entries (#19824) 2020-09-12 13:05:52 -04:00
.nvmrc Upgrade node.js to 20 LTS (#32855) 2025-04-14 12:52:02 -04:00
.prettierignore [prettier] Ignore compiler/target (#31168) 2024-10-10 10:53:27 -04:00
.prettierrc.js [scripts] Switch back to flow parser for prettier (#33414) 2025-06-03 00:00:28 -04:00
.watchmanconfig .watchmanconfig must be valid json (#16118) 2019-07-11 19:01:02 -07:00
babel.config-react-compiler.js feat(eslint-plugin-react-hooks): merge rule from eslint-plugin-react-compiler into react-hooks plugin (#32416) 2025-03-12 21:43:06 -04:00
babel.config-ts.js Update babel configs used in jest (#32588) 2025-03-12 19:07:39 -04:00
babel.config.js Partially revert #32588 (#32621) 2025-03-15 15:21:57 -04:00
CHANGELOG.md Clean up 19.1.1 changelog (#34023) 2025-07-28 17:32:23 +01:00
CODE_OF_CONDUCT.md revert last grammatical edit (#25067) 2022-08-10 20:14:31 +01:00
CONTRIBUTING.md Fix: Updated link in CONTRIBUTING (#25381) 2022-10-03 10:29:57 -04:00
dangerfile.js Fix typo in dangerfile.js which results in an unreachable code path… (#32277) 2025-01-31 01:44:02 -05:00
LICENSE [Codemod] Update copyright header to Meta (#25315) 2022-10-18 11:19:24 -04:00
MAINTAINERS Update MAINTAINERS (#32238) 2025-01-27 13:40:45 -06:00
package.json [tests] remove pretest compiler script (#33452) 2025-06-06 09:16:58 -04:00
react.code-workspace created a vscode workspace file for the repo (#29830) 2024-06-13 16:23:42 +01:00
ReactVersions.js [eprh] Bump stable version (#32978) 2025-04-21 14:36:13 -04:00
README.md [ez] Remove circleci badge from readme 2024-07-29 13:26:14 -04:00
SECURITY.md Create SECURITY.md (#15784) 2020-01-09 14:07:41 -08:00
yarn.lock [scripts] Switch back to flow parser for prettier (#33414) 2025-06-03 00:00:28 -04:00

React · GitHub license npm version (Runtime) Build and Test (Compiler) TypeScript PRs Welcome

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:

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:

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.