astro/packages/integrations/svelte/server.js

import SvelteWrapper from './Wrapper.svelte.ssr.js';

function check(Component) {
	return Component['render'] && Component['$$render'];
}

async function renderToStaticMarkup(Component, props, children) {
	const { html } = SvelteWrapper.render({
		__astro_component: Component,
		__astro_children: children,
		...props,
	});
	return { html };
}

export default {
	check,
	renderToStaticMarkup,
};