mirror of
https://github.com/facebook/react.git
synced 2025-11-01 09:12:30 +00:00
Jack Pope
1beb73de0f
Following #28768, add a path to testing Fast JSX on www. We want to measure the impact of Fast JSX and enable a path to testing before string refs are completely removed in www (which is a work in progress). Without `disableStringRefs`, we need to copy any object with a `ref` key so we can pass it through `coerceStringRef()` and copy it into the object. This de-opt path is what is gated behind `enableFastJSXWithStringRefs`. The additional checks should have no perf impact in OSS as the flags remain true there and the build output is not changed. For www, I've benchmarked the addition of the boolean checks with values cached at module scope. There is no significant change observed from our benchmarks and any latency will apply to test and control branches evenly. This added experiment complexity is temporary. We should be able to clean it up, along with the flag checks for `enableRefAsProp` and `disableStringRefs` shortly.
react
React is a JavaScript library for creating user interfaces.
The react package contains only the functionality necessary to define React components. It is typically used together with a React renderer like react-dom for the web, or react-native for the native environments.
Note: by default, React will be in development mode. The development version includes extra warnings about common mistakes, whereas the production version includes extra performance optimizations and strips all error messages. Don't forget to use the production build when deploying your application.
Usage
import { useState } from 'react';
import { createRoot } from 'react-dom/client';
function Counter() {
const [count, setCount] = useState(0);
return (
<>
<h1>{count}</h1>
<button onClick={() => setCount(count + 1)}>
Increment
</button>
</>
);
}
const root = createRoot(document.getElementById('root'));
root.render(<Counter />);