## Summary Removes the usage of `consoleManagedByDevToolsDuringStrictMode` flag from React DevTools backend, this is the only place in RDT where this flag was used. The only remaining part is [`ReactFiberDevToolsHook`](6708115937/packages/react-reconciler/src/ReactFiberDevToolsHook.js (L203)), so React renderers can start notifying DevTools when `render` runs in a Strict Mode. > TL;DR: it is broken, and we already incorrectly apply dimming, when RDT frontend is not opened. Fixing in the next few changes, see next steps. Before explaining why I am removing this, some context is required. The way RDT works is slightly different, based on the fact if RDT frontend and RDT backend are actually connected: 1. For browser extension case, the Backend is a script, which is injected by the extension when page is loaded and before React is loaded. RDT Frontend is loaded together with the RDT panel in browser DevTools, so ONLY when user actually opens the RDT panel. 2. For native case, RDT backend is shipped together with `react-native` for DEV bundles. It is always injected before React is loaded. RDT frontend is loaded only when user starts a standalone RDT app via `npx react-devtools` or by opening React Native DevTools and then selecting React DevTools panel. When Frontend is not connected to the Backend, the only thing we have is the `__REACT_DEVTOOLS_GLOBAL_HOOK__` — this thing inlines some APIs in itself, so that it can work similarly when RDT Frontend is not even opened. This is especially important for console logs, since they are cached and stored, then later displayed to the user once the Console panel is opened, but from RDT side, you want to modify these console logs when they are emitted. In order to do so, we [inline the console patching logic into the hook](3ac551e855/packages/react-devtools-shared/src/hook.js (L222-L319)). This implementation doesn't use the `consoleManagedByDevToolsDuringStrictMode`. This means that if we enable `consoleManagedByDevToolsDuringStrictMode` for Native right now, users would see broken dimming in LogBox / Metro logs when RDT Frontend is not opened. Next steps: 1. Align this console patching implementation with the one in `hook.js`. 2. Make LogBox compatible with console stylings: both css and ASCII escape symbols. 3. Ship new version of RDT with these changes. 4. Remove `consoleManagedByDevToolsDuringStrictMode` from `ReactFiberDevToolsHook`, so this is rolled out for all renderers.
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.