astro/packages/integrations/react/server.js

import React from 'react';
import ReactDOM from 'react-dom/server.js';
import StaticHtml from './static-html.js';

const reactTypeof = Symbol.for('react.element');

function errorIsComingFromPreactComponent(err) {
	return err.message && (err.message.startsWith("Cannot read property '__H'") || err.message.includes("(reading '__H')"));
}

function check(Component, props, children) {
	// Note: there are packages that do some unholy things to create "components".
	// Checking the $$typeof property catches most of these patterns.
	if (typeof Component === 'object') {
		const $$typeof = Component['$$typeof'];
		return $$typeof && $$typeof.toString().slice('Symbol('.length).startsWith('react');
	}
	if (typeof Component !== 'function') return false;

	if (Component.prototype != null && typeof Component.prototype.render === 'function') {
		return React.Component.isPrototypeOf(Component) || React.PureComponent.isPrototypeOf(Component);
	}

	let error = null;
	let isReactComponent = false;
	function Tester(...args) {
		try {
			const vnode = Component(...args);
			if (vnode && vnode['$$typeof'] === reactTypeof) {
				isReactComponent = true;
			}
		} catch (err) {
			if (!errorIsComingFromPreactComponent(err)) {
				error = err;
			}
		}

		return React.createElement('div');
	}

	renderToStaticMarkup(Tester, props, children, {});

	if (error) {
		throw error;
	}
	return isReactComponent;
}

function renderToStaticMarkup(Component, props, children, metadata) {
	delete props['class'];
	const vnode = React.createElement(Component, {
		...props,
		children: children != null ? React.createElement(StaticHtml, { value: children }) : undefined,
	});
	let html;
	if (metadata && metadata.hydrate) {
		html = ReactDOM.renderToString(vnode);
	} else {
		html = ReactDOM.renderToStaticMarkup(vnode);
	}
	return { html };
}

export default {
	check,
	renderToStaticMarkup,
};