Sebastian Markbåge
acabf11245
* Update Flow
* Fix createElement() issue
The * type was too ambiguous. It's always a string so what's the point?
Suppression for missing Flow support for {is: ''} web component argument to createElement() didn't work for some reason.
I don't understand what the regex is testing for anyway (a task number?) so I just removed that, and suppression got fixed.
* Remove deleted $Abstract<> feature
* Expand the unsound isAsync check
Flow now errors earlier because it can't find .type on a portal.
* Add an unsafe cast for the null State in UpdateQueue
* Introduce "hydratable instance" type
The Flow error here highlighted a quirk in our typing of hydration.
React only really knows about a subset of all possible nodes that can
exist in a hydrated tree. Currently we assume that the host renderer
filters them out to be either Instance or TextInstance. We also assume
that those are different things which they might not be. E.g. it could
be fine for a renderer to render "text" as the same type as one of the
instances, with some default props.
We don't really know what it will be narrowed down to until we call
canHydrateInstance or canHydrateTextInstance. That's when the type is
truly refined.
So to solve this I use a different type for hydratable instance that is
used in that temporary stage between us reading it from the DOM and until
it gets refined by canHydrate(Text)Instance.
* Have the renderer refine Hydratable Instance to Instance or Text Instance
Currently we assume that if canHydrateInstance or canHydrateTextInstance
returns true, then the types also match up. But we don't tell that to Flow.
It just happens to work because `fiber.stateNode` is still `any`.
We could potentially use some kind of predicate typing but instead
of that I can just return null or instance from the "can" tests.
This ensures that the renderer has to do the refinement properly.
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.
Documentation
You can find the React documentation on the website.
It 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:
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.
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.