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Andrew Clark
ed3c65caf0
We want to warn if we detect that an app is using an outdated JSX transform. We can't just warn if `createElement` is called because we still support `createElement` when it's called manually. We only want to warn if `createElement` is output by the compiler. The heuristic is to check for a `__self` prop, which is an optional, internal prop that older transforms used to pass to `createElement` for better debugging in development mode. If `__self` is present, we `console.warn` once with advice to upgrade to the modern JSX transform. Subsequent elements will not warn. There's a special case we have to account for: when a static "key" prop is defined _after_ a spread, the modern JSX transform outputs `createElement` instead of `jsx`. (This is because with `jsx`, a spread key always takes precedence over a static key, regardless of the order, whereas `createElement` respects the order.) To avoid a false positive warning, we skip the warning whenever a `key` prop is present.
react-dom
This package serves as the entry point to the DOM and server renderers for React. It is intended to be paired with the generic React package, which is shipped as react to npm.
Installation
npm install react react-dom
Usage
In the browser
import { createRoot } from 'react-dom/client';
function App() {
return <div>Hello World</div>;
}
const root = createRoot(document.getElementById('root'));
root.render(<App />);
On the server
import { renderToPipeableStream } from 'react-dom/server';
function App() {
return <div>Hello World</div>;
}
function handleRequest(res) {
// ... in your server handler ...
const stream = renderToPipeableStream(<App />, {
onShellReady() {
res.statusCode = 200;
res.setHeader('Content-type', 'text/html');
stream.pipe(res);
},
// ...
});
}
API
react-dom
See https://react.dev/reference/react-dom
react-dom/client
See https://react.dev/reference/react-dom/client