587f03c922
This is the beginning of a refactor of the DevTools Fiber backend. The new approach is basically that we listen to each commit from Fiber and traverse the tree - building up a filtered shadow tree. Then we send diffs based on that tree and perform our own operations against that instead of using Fibers as the source of truth. Fiber diffs Elements -> Fibers. The backend diffs Fibers -> DevToolsInstances as a side-effect it sends deltas to the front end. This makes the algorithm resilient to a different Fiber implementation that doesn't use pairs of Fibers (alternates) but instead stateless new clones each time. In that world we can't treat Fibers as instances. They can hold onto instances but they're not necessarily 1:1 themselves. The same thing also applies to Server Components that don't have their own instances. The algorithm is more or less the same as React's reconciliation in ReactChildFiber itself. However, we do a mutable update of the tree as we go. We also cheat a bit here in the first version in that we still have fiberToFiberInstance map and alternate which makes reorders easier. Further down we could do the reorders by adding the previous set to a temporary map like ChildFiber does but only if they're not already in order. This first bit is just about making sure that we produce correct trees. We have fairly good test coverage already of that already. In the next few follow ups I'll start simplifying the rest of the logic by taking advantage of the new tree.
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.