Nicolas GallagherandGitHub
c187937667
This is a partial replacement for the 'Press' responder: 1. `useTap` is scoped to pointers (no keyboard support). Our current thinking is that "responders" should be limited to working with pointers, and that they can be combined with 'useKeyboard' in user-space. For example, we might create a 'usePress' hook in user-space that combines 'useTap' with 'useKeyboard' to react to both pointers and keyboard interactions. 2. `useTap` cancels the gesture once the pointer moves over an element that is not within the responder target's subtree. This differs from `usePress` (and React Native), where the gesture remains active after the pointer exits the target's subtree and is restarted once the pointer reenters. One of the drawbacks with the `usePress` behavior is that it requires repeatedly measuring DOM elements (which can cause jank) to perform hit region tests. `useTap` avoids doing this and relies on `document.elementFromPoint` only to support the TouchEvent fallbacks. 3. `useTap` calls `onTapUpdate` when the active gesture's state changes, `onTapEnd` when the gesture successfully completes. and `onTapCancel` when it fails. There is no `onTap` callback. `usePress` did not explicitly report back when the gesture failed, and product developers were confused about the difference between `onPress` and `onPressEnd`. 4. `useTap` explicitly separates the PointerEvent implementation from the MouseEvent/TouchEvent fallback. 5. `useTap` has better unit test coverage . All pointer types and the fallback environment are tested. The shape of the gesture state object is also defined and tested.
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 to evolve 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.