Andrew ClarkandGitHub
cd641d0ffc
* Use performFailedUnitOfWork instead of beginFailedWork and completeUnitOfWork separately. Also, we unwind the context stack *before* beginning work again. * Only use error loop directly after a commit We have a special, forked version of work loop that checks if a fiber is in a failed state (needs to be unmounted). This is only relevant right after a commit -- begin phase errors are handled differently, by unwinding the stack. Also renamed findNextUnitOfWork to resetNextUnitOfWork and made it a void function to signal that it's impure. * Reset nextUnitOfWork after every commit * Include the error boundary when unwinding a failed subtree Also added a warning to the error boundary to show that it failed. * Push context providers in beginFailedWork to avoid push/pop mismatch Added a test that demonstrates how an error boundary that is also a context provider could pop its context too many times if you neglect to push it in beginFailedWork. This happens because we've already popped the context once in unwindContext. The solution is a code smell. I don't like how we push/pop context in so many places. Shouldn't they all happen in the same location? * Refactor work loop - Optimizes the normal, non-error path by reducing the number of checks needed to begin performing work. - Prevents control flow from oscillating between fast normal loop and slower error loop. * Improve context unwinding test Tests that we correctly unwind an error boundary that is also a context provider. * Triangle tester should assert the tree is consistent after every action ...not just at the end. * Better implementation of infinite loop error Infinite loops should only be possible if a while loop never terminates. Now that we've refactored to avoid oscillation between different work loops, we can count updates local to each loop. The two loops that could infinite loop are the sync work loop and the loop that surrounds the body of the render phase catch block. The async loop could also fall into an infinite loop if the deadline never terminates, but we'll assume that it always eventually does. This change also creates better error stack traces because the error is thrown from inside the first setState that exceeds the limit. Added a test case for an error boundary whose parent remounts it on recovery. * Use invokeGuardedCallback in DEV
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.
Examples
We have several examples on the website. Here is the first one to get you started:
class HelloMessage extends React.Component {
render() {
return <div>Hello {this.props.name}</div>;
}
}
ReactDOM.render(
<HelloMessage name="John" />,
document.getElementById('container')
);
This example will render "Hello John" 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. We recommend using Babel with a React preset to convert JSX into native JavaScript for browsers to digest.
Installation
React is available as the react package on npm. It is also available on a CDN.
React is flexible and can be used in a variety of projects. You can create new apps with it, but you can also gradually introduce it into an existing codebase without doing a rewrite.
The recommended way to install React depends on your project. Here you can find short guides for the most common scenarios:
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.
Beginner Friendly Bugs
To help you get your feet wet and get you familiar with our contribution process, we have a list of beginner friendly bugs that contain bugs which are fairly easy to fix. This is a great place to get started.
License
React is BSD licensed. We also provide an additional patent grant.
React documentation is Creative Commons licensed.
Examples provided in this repository and in the documentation are separately licensed.