47d0c30246
Host Components can exist as four semantic types 1. regular Components (Vanilla obv) 2. singleton Components 2. hoistable components 3. resources Each of these component types have their own rules related to mounting and reconciliation however they are not direclty modeled as their own unique fiber type. This is partly for code size but also because reconciling the inner type of these components would be in a very hot path in fiber creation and reconciliation and it's just not practical to do this logic check here. Right now we have three Fiber types used to implement these 4 concepts but we probably need to reconsider the model and think of Host Components as a single fiber type with an inner implementation. Once we do this we can regularize things like transitioning between a resource and a regular component or a singleton and a hoistable instance. The cases where these transitions happen today aren't particularly common but they can be observed and currently the handling of these transitions is incomplete at best and buggy at worst. The most egregious case is the link type. This can be a regular component (stylesheet without precedence) a hoistable component (non stylesheet link tags) or a resource (stylesheet with a precedence) and if you have a single jsx slot that tries to reconcile transitions between these types it just doesn't work well. This commit adds an error for when a Hoistable goes from Instance to Resource. Currently this is only possible for `<link>` elements going to and from stylesheets with precedence. Hopefully we'll be able to remove this error and implement as an inner type before we encounter new categories for the Hoistable types detecting type shifting to and from regular components is harder to do efficiently because we don't want to reevaluate the type on every update for host components which is currently not required and would add overhead to a very hot path singletons can't really type shift in their one practical implementation (DOM) so they are only a problem in theroy not practice
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.