Andrew Clark
87ae211ccd
* New context API Introduces a declarative context API that propagates updates even when shouldComponentUpdate returns false. * Fuzz tester for context * Use ReactElement for provider and consumer children * Unify more branches in createFiberFromElement * Compare context values using Object.is Same semantics as PureComponent/shallowEqual. * Add support for Provider and Consumer to server-side renderer * Store providers on global stack Rather than using a linked list stored on the context type. The global stack can be reset in case of an interruption or error, whereas with the linked list implementation, you'd need to keep track of every context type. * Put new context API behind a feature flag We'll enable this in www only for now. * Store nearest provider on context object * Handle reentrancy in server renderer Context stack should be per server renderer instance. * Bailout of consumer updates using bitmask The context type defines an optional function that compares two context values, returning a bitfield. A consumer may specify the bits it needs for rendering. If a provider's context changes, and the consumer's bits do not intersect with the changed bits, we can skip the consumer. This is similar to how selectors are used in Redux but fast enough to do while scanning the tree. The only user code involved is the function that computes the changed bits. But that's only called once per provider update, not for every consumer. * Store current value and changed bits on context object There are fewer providers than consumers, so better to do this work at the provider. * Use maximum of 31 bits for bitmask This is the largest integer size in V8 on 32-bit systems. Warn in development if too large a number is used. * ProviderComponent -> ContextProvider, ConsumerComponent -> ContextConsumer * Inline Object.is * Warn if multiple renderers concurrently render the same context provider Let's see if we can get away with not supporting this for now. If it turns out that it's needed, we can fall back to backtracking the fiber return path. * Nits that came up during review
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.