monaco-editor/test/manual/2040/iframe.js

const init = () => {
	loadEditor(function () {
		// create the editor
		const target = document.getElementById('container');
		const editor = monaco.editor.create(target, { language: 'html' });

		// load some sample data
		(async () => {
			const response = await fetch('https://microsoft.github.io/monaco-editor/');
			const html = await response.text();
			editor.getModel().setValue(html);
		})();
	});
};

window.addEventListener('DOMContentLoaded', () => {
	if (!window.innerWidth || !window.innerHeight) {
		window.addEventListener('resize', init, { once: true });
	} else {
		init();
	}
});