Sebastian Markbåge
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Stacked on #28853 and #28854. React supports rendering `Iterable` and will soon support `AsyncIterable`. As long as it's multi-shot since during an update we may have to rerender with new inputs an loop over the iterable again. Therefore the `Iterator` and `AsyncIterator` types are not supported directly as a child of React - and really it shouldn't pass between Hooks or components neither for this reason. For parity, that's also the case when used in Server Components. However, there is a special case when the component rendered itself is a generator function. While it returns as a child an `Iterator`, the React Element itself can act as an `Iterable` because we can re-evaluate the function to create a new generator whenever we need to. It's also very convenient to use generator functions over constructing an `AsyncIterable`. So this is a proposal to special case the `Generator`/`AsyncGenerator` returned by a (Async) Generator Function. In Flight this means that when we render a Server Component we can serialize this value as an `Iterable`/`AsyncIterable` since that's effectively what rendering it on the server reduces down to. That way if Fiber can receive the result in any position. For SuspenseList this would also need another special case because the children of SuspenseList represent "rows". `<SuspenseList><Component /></SuspenseList>` currently is a single "row" even if the component renders multiple children or is an iterator. This is currently different if Component is a Server Component because it'll reduce down to an array/AsyncIterable and therefore be treated as one row per its child. This is different from `<SuspenseList><Component /><Component /></SuspenseList>` since that has a wrapper array and so this is always two rows. It probably makes sense to special case a single-element child in `SuspenseList` to represent a component that generates rows. That way you can use an `AsyncGeneratorFunction` to do this.
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.