013b7ad117
* Outline push/pop logic in `renderRoot` I want to get rid of the the `isSync` argument to `renderRoot`, and instead use separate functions for concurrent and synchronous render. As a first step, this extracts the push/pop logic that happens before and after the render phase into helper functions. * Extract `catch` block into helper function Similar to previous commit. Extract error handling logic into a separate function so it can be reused. * Fork `renderRoot` for sync and concurrent Removes `isSync` argument in favor of separate functions. * Extra "root completion" logic to separate function Moving this out to avoid an accidental early return, which would bypass the call to `ensureRootIsScheduled` and freeze the UI. * Inline `renderRoot` Inlines `renderRoot` into `performConcurrentWorkOnRoot` and `performSyncWorkOnRoot`. This lets me remove the `isSync` argument and also get rid of a redundant try-catch wrapper. * [suspense][error handling] Add failing unit test Covers an edge case where an error is thrown inside the complete phase of a component that is in the return path of a component that suspends. The second error should also be handled (i.e. able to be captured by an error boundary. The test is currently failing because there's a call to `completeUnitOfWork` inside the main render phase `catch` block. That call is not itself wrapped in try-catch, so anything that throws is treated as a fatal/unhandled error. I believe this bug is only observable if something in the host config throws; and, only in legacy mode, because in concurrent/batched mode, `completeUnitOfWork` on fiber that throws follows the "unwind" path only, not the "complete" path, and the "unwind" path does not call any host config methods. * [scheduler][profiler] Start time of delayed tasks Fixes a bug in the Scheduler profiler where the start time of a delayed tasks is always 0. * Remove ad hoc `throw` Fatal errors (errors that are not captured by an error boundary) are currently rethrown from directly inside the render phase's `catch` block. This is a refactor hazard because the code in this branch has to mirror the code that happens at the end of the function, when exiting the render phase in the normal case. This commit moves the throw to the end, using a new root exit status. * Handle errors that occur on unwind
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.