Luna Ruan
f512537754
This babel transform is a fork of the @babel/plugin-transform-react-jsx transform and is for experimentation purposes only. We don't plan to own this code in the future, and we will upstream this to Babel at some point once we've proven out the concept.
As per the RFC to simplify element creation, we want to change the JSX transform from targeting React.createElement(type, props, children) to React.jsx(type, props, key). This modifies the existing @babel/plugin-transform-react-jsx (and helper) babel plugin to support React.jsx and React.jsxDEV.
The main differences between React.jsx/React.jsxDEV and React.createElement are:
1.) key is now passed as an explicit argument rather than through props
3.) children are now passed through props rather than as an explicit argument
4.) props must always be an object
5.) __source and and __self are now passed as separate arguments into React.jsxDEV rather than through props
Part of the rationale for this change is that we want to deprecate key spread through props because this is an expensive dynamic comparison operation. We want users instead always explicitly pass key as a prop. However, in the interim, we need a way to distinguish between <div {...props} key={foo} /> and <div key={foo} {...props} />. Therefore, until we completely deprecate key spreading, we will use React.createElement to transform <div {...props} key="Hi" /> and React.jsx to transform everything else.
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.