fdad813ac7
Stacked on #26570 Previously we restricted Float methods to only being callable while rendering. This allowed us to make associations between calls and their position in the DOM tree, for instance hoisting preinitialized styles into a ShadowRoot or an iframe Document. When considering how we are going to support Flight support in Float however it became clear that this restriction would lead to compromises on the implementation because the Flight client does not execute within the context of a client render. We want to be able to disaptch Float directives coming from Flight as soon as possible and this requires being able to call them outside of render. this patch modifies Float so that its methods are callable anywhere. The main consequence of this change is Float will always use the Document the renderer script is running within as the HoistableRoot. This means if you preinit as style inside a component render targeting a ShadowRoot the style will load in the ownerDocument not the ShadowRoot. Practially speaking it means that preinit is not useful inside ShadowRoots and iframes. This tradeoff was deemed acceptable because these methods are optimistic, not critical. Additionally, the other methods, preconntect, prefetchDNS, and preload, are not impacted because they already operated at the level of the ownerDocument and really only interface with the Network cache layer. I added a couple additional fixes that were necessary for getting tests to pass that are worth considering separately. The first commit improves the diff for `waitForThrow` so it compares strings if possible. The second commit makes invokeGuardedCallback not use metaprogramming pattern and swallows any novel errors produced from trying to run the guarded callback. Swallowing may not be the best we can do but it at least protects React against rapid failure when something causes the dispatchEvent to throw.
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 Online Playgrounds to get a taste of React.
- Add React to a Website as a
<script>tag in one minute. - Create a New React App if you're looking for a powerful JavaScript toolchain.
You can use React as a <script> tag from a CDN, or as a react package on npm.
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. If you're using React as a <script> tag, read this section on integrating JSX; otherwise, the recommended JavaScript toolchains handle it automatically.
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.