export default {
  async fetch(req) {
    const url = new URL(req.url);
    const target = url.searchParams.get("url");
    if (!target) {
      return new Response(`
        <form>
          <input name="url" placeholder="https://example.com" style="width:70%">
          <button type="submit">Go</button>
        </form>
      `, { headers: { "content-type": "text/html" } });
    }
    const r = await fetch(target);
    return r;
  }
};

<script defer data-domain="html.cafe" src="https://milkymouse.com/js/script.js"></script>