javascript: (function () {
  if (
    location.host.includes("youtube.com") &&
    (location.pathname.startsWith("/channel") ||
      location.pathname.startsWith("/@"))
  ) {
    const feed = document
      .querySelector("link[title='RSS']")
      .getAttribute("href");
    if (feed.includes(".xml")) {
      let toClip = prompt("copy to clipboard", feed);
      navigator.clipboard.writeText(toClip);
    } else {
      window.alert("failed");
    }
  } else {
    window.alert("current page isn't YouTube Channel");
  }
})();