Andrew ClarkandGitHub
b4145cf2fe
* Add `supportsMicrotasks` to the host config Only certain renderers support scheduling a microtask, so we need a renderer specific flag that we can toggle. That way it's off for some renderers and on for others. I copied the approach we use for the other optional parts of the host config, like persistent mode and test selectors. Why isn't the feature flag sufficient? The feature flag modules, confusingly, are not renderer-specific, at least when running the our tests against the source files. They are meant to correspond to a release channel, not a renderer, but we got confused at some point and haven't cleaned it up. For example, when we run `yarn test`, Jest loads the flags from the default `ReactFeatureFlags.js` module, even when we import the React Native renderer — but in the actual builds, we load a different feature flag module, `ReactFeatureFlags.native-oss.js.` There's no way in our current Jest load a different host config for each renderer, because they all just import the same module. We should solve this by creating separate Jest project for each renderer, so that the flags loaded when running against source are the same ones that we use in the compiled bundles. The feature flag (`enableDiscreteMicrotasks`) still exists — it's used to set the React DOM host config's `supportsMicrotasks` flag to `true`. (Same for React Noop) The important part is that turning on the feature flag does *not* affect the other renderers, like React Native. The host config will likely outlive the feature flag, too, since the feature flag only exists so we can gradually roll it out and measure the impact in production; once we do, we'll remove it. Whereas the host config flag may continue to be used to disable the discrete microtask behavior for RN, because RN will likely use a native (non-JavaScript) API to schedule its tasks. * Add `supportsMicrotask` to react-reconciler README
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.