978fae4b4f
This PR is now based on #26256 The original matching function for `hydrateHoistable` some challenging time complexity since we built up the list of matchable nodes for each link of that type and then had to check to exclusion. This new implementation aims to improve the complexity For hoisted title tags we match the first title if it is valid (not in SVG context and does not have `itemprop`, the two ways you opt out of hoisting when rendering titles). This path is much faster than others and we use it because valid Documents only have 1 title anyway and if we did have a mismatch the rendered title still ends up as the Document.title so there is no functional degradation for misses. For hoisted link and meta tags we track all potentially hydratable Elements of this type in a cache per Document. The cache is refreshed once each commit if and only if there is a title or meta hoistable hydrating. The caches are partitioned by a natural key for each type (href for link and content for meta). Then secondary attributes are checked to see if the potential match is matchable. For link we check `rel`, `title`, and `crossorigin`. These should provide enough entropy that we never have collisions except is contrived cases and even then it should not affect functionality of the page. This should also be tolerant of links being injected in arbitrary places in the Document by 3rd party scripts and browser extensions For meta we check `name`, `property`, `http-equiv`, and `charset`. These should provide enough entropy that we don't have meaningful collisions. It is concievable with og tags that there may be true duplciates `<meta property="og:image:size:height" content="100" />` but even if we did bind to the wrong instance meta tags are typically only read from SSR by bots and rarely inserted by 3rd parties so an adverse functional outcome is not expected. |
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README.md
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.