eeabb7312f
There are four places we have special cases based off the DOMProperty config: 1) DEV-only: ReactDOMUnknownPropertyHook warns for passing booleans to non-boolean attributes. We just need a simple list of all properties that are affected by that. We could probably move this in under setProp instead and have it covered by that list. 2) DEV-only: Hydration. This just needs to read the value from an attribute and compare it to what we'd expect to see if it was rendered on the client. This could use some simplification/unification of the code but I decided to just keep it simple and duplicated since code size isn't an issue. 3) DOMServerFormatConfig pushAttribute: This just maps the special case to how to emit it as a HTML attribute. 4) ReactDOMComponent setProp: This just maps the special case to how to emit it as setAttribute or removeAttribute. Basically we just have to remember to keep pushAttribute and setProp aligned. There's only one long switch in prod per environment. This just turns it all to a giant simple switch statement with string cases. This is in theory the most optimizable since syntactically all the information for a hash table is there. However, unfortunately we know that most VMs don't optimize this very well and instead just turn them into a bunch of ifs. JSC is best. We can minimize the cost by just moving common attribute to the beginning of the list. If we shipped this, maybe VMs will get it together to start optimizing this case but there's a chicken and egg problem here and the game theory reality is that we probably don't want to regress. Therefore, I intend to do a follow up after landing this which reintroduces an object indirection for simple property aliases. That should be enough to make the remaining cases palatable. I'll also extract the most common attributes to the beginning or separate ifs. Ran attribute-behavior fixture and the table is the same.
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 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:
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. 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 that have a relatively limited scope. This is a great place to get started.
License
React is MIT licensed.