* Refactor Flight to require a module reference to be brand checked This exposes a host environment (bundler) specific hook to check if an object is a module reference. This will be used so that they can be passed directly into Flight without needing additional wrapper objects. * Emit module references as a special type of value We already have JSON and errors as special types of "rows". This encodes module references as a special type of row value. This was always the intention because it allows those values to be emitted first in the stream so that as a large models stream down, we can start preloading as early as possible. We preload the module when they resolve but we lazily require them as they are referenced. * Emit module references where ever they occur This emits module references where ever they occur. In blocks or even directly in elements. * Don't special case the root row I originally did this so that a simple stream is also just plain JSON. However, since we might want to emit things like modules before the root module in the stream, this gets unnecessarily complicated. We could add this back as a special case if it's the first byte written but meh. * Update the protocol * Add test for using a module reference as a client component * Relax element type check Since Flight now accepts a module reference as returned by any bundler system, depending on the renderer running. We need to drastically relax the check to include all of them. We can add more as we discover them. * Move flow annotation Seems like our compiler is not happy with stripping this. * Some bookkeeping bug * Can't use the private field to check
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 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 own 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:
function HelloMessage({ name }) {
return <div>Hello {name}</div>;
}
ReactDOM.render(
<HelloMessage name="Taylor" />,
document.getElementById('container')
);
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 which have a relatively limited scope. This is a great place to get started.
License
React is MIT licensed.