1e241f9d6c
Follow up to #30105. This supports `renderToMarkup` in a non-RSC environment (not the `react-server` condition). This is just a Fizz renderer but it errors at runtime when you use state, effects or event handlers that would require hydration - like the RSC version would. (Except RSC can give early errors too.) To do this I have to move the `react-html` builds to a new `markup` dimension out of the `dom-legacy` dimension so that we can configure this differently from `renderToString`/`renderToStaticMarkup`. Eventually that dimension can go away though if deprecated. That also helps us avoid dynamic configuration and we can just compile in the right configuration so the split helps anyway. One consideration is that if a compiler strips out useEffects or inlines initial state from useState, then it would not get called an the error wouldn't happen. Therefore to preserve semantics, a compiler would need to inject some call that can check the current renderer and whether it should throw. There is an argument that it could be useful to not error for these because it's possible to write components that works with SSR but are just optionally hydrated. However, there's also an argument that doing that silently is too easy to lead to mistakes and it's better to error - especially for the e-mail use case where you can't take it back but you can replay a queue that had failures. There are other ways to conditionally branch components intentionally. Besides if you want it to be silent you can still use renderToString (or better yet renderToReadableStream). The primary mechanism is the RSC environment and the client-environment is really the secondary one that's only there to support legacy environments. So this also ensures parity with the primary environment.
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.