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When deeply nested Suspense boundaries inside a fallback of another boundary resolve it is possible to encounter situations where you either attempt to flush an aborted Segment or you have a boundary without any root segment. We intended for both of these conditions to be impossible to arrive at legitimately however it turns out in this situation you can. The fix is two-fold 1. allow flushing aborted segments by simply skipping them. This does remove some protection against future misconfiguraiton of React because it is no longer an invariant that you hsould never attempt to flush an aborted segment but there are legitimate cases where this can come up and simply omitting the segment is fine b/c we know that the user will never observe this. A semantically better solution would be to avoid flushing boudaries inside an unneeded fallback but to do this we would need to track all boundaries inside a fallback or create back pointers which add to memory overhead and possibly make GC harder to do efficiently. By flushing extra we're maintaining status quo and only suffer in performance not with broken semantics. 2. when queuing completed segments allow for queueing aborted segments and if we are eliding the enqueued segment allow for child segments that are errored to be enqueued too. This will mean that we can maintain the invariant that a boundary must have a root segment the first time we flush it, it just might be aborted (see point 1 above). This change has two seemingly similar test cases to exercise this fix. The reason we need both is that when you have empty segments you hit different code paths within Fizz and so each one (without this fix) triggers a different error pathway. This change also includes a fix to our tests where we were not appropriately setting CSPnonce back to null at the start of each test so in some contexts scripts would not run for some tests
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.