Return small HTML page
Deliver an HTML page from an HTML string directly inside the Worker script.
const html = `<!DOCTYPE html><body>  <h1>Hello World</h1>  <p>This markup was generated by a Cloudflare Worker.</p></body>`;
async function handleRequest(request) {  return new Response(html, {    headers: {      'content-type': 'text/html;charset=UTF-8',    },  });
}
addEventListener('fetch', event => {  return event.respondWith(handleRequest(event.request));
});