copy-title-and-url.js

const title = document.title;
const url = location.href;
function listener(e) {
  e.clipboardData.setData("text/html", `<a href="${url}">${title}</a>`);
  e.clipboardData.setData("text/plain", `[${title}](${url})`);
  e.preventDefault();
}
document.addEventListener("copy", listener);
document.execCommand("copy");
document.removeEventListener("copy", listener);

TODO: Escape the title properly