b229f540e2
This adds a new DEV-only row type `D` for DebugInfo. If we see this in prod, that's an error. It can contain extra debug information about the Server Components (or Promises) that were compiled away during the server render. It's DEV-only since this can contain sensitive information (similar to errors) and since it'll be a lot of data, but it's worth using the same stream for simplicity rather than a side-channel. In this first pass it's just the Server Component's name but I'll keep adding more debug info to the stream, and it won't always just be a Server Component's stack frame. Each row can get more debug rows data streaming in as it resolves and renders multiple server components in a row. The data structure is just a side-channel and it would be perfectly fine to ignore the D rows and it would behave the same as prod. With this data structure though the data is associated with the row ID / chunk, so you can't have inline meta data. This means that an inline Server Component that doesn't get an ID otherwise will need to be outlined. The way I outline Server Components is using a direct reference where it's synchronous though so on the client side it behaves the same (i.e. there's no lazy wrapper in this case). In most cases the `_debugInfo` is on the Promises that we yield and we also expose this on the `React.Lazy` wrappers. In the case where it's a synchronous render it might attach this data to Elements or Arrays (fragments) too. In a future PR I'll wire this information up with Fiber to stash it in the Fiber data structures so that DevTools can pick it up. This property and the information in it is not limited to Server Components. The name of the property that we look for probably shouldn't be `_debugInfo` since it's semi-public. Should consider the name we use for that. If it's a synchronous render that returns a string or number (text node) then we don't have anywhere to attach them to. We could add a `React.Lazy` wrapper for those but I chose to prioritize keeping the data structure untouched. Can be useful if you use Server Components to render data instead of React Nodes.
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.