add xReddit buttons to Old Reddit Posts

const setupMorePostsObserver = (functionTocall) => {
  // set up a mutation observer to modify the post bottom bar when new posts are loaded
  const postBottomBarObserver = new MutationObserver((mutations) => {
    const hasAddedNodes = mutations.some((mutation) => {
      // check if the added node is a thing link
      return (
        mutation.addedNodes.length > 0 &&
        ($(mutation.addedNodes[0]).is(".thing.link") ||
          $(mutation.addedNodes[0]).is(".sitetable")) // in case of infinite scroll
      );
    });
    if (hasAddedNodes) {
      // call the function to modify the post
      functionTocall();
    }
  });

  // observe the body for new posts
  postBottomBarObserver.observe(document, {
    childList: true,
    subtree: true,
  });
};

const addXRedditButtons = () => {
  const thingLinks = $(".thing.link").not(".xreddit-modified");

  thingLinks.each((index, element) => {
    // mark the post as modified
    $(element).addClass("xreddit-modified");

    const thingLinkHref = $(element).attr("data-permalink");

    const buttonList = $(element).find(".flat-list.buttons");
    // add buttons for vxreddit and rxddit

    const vxredditButton = $(
      `<li><a href="javascript:;" class="xreddit-button">vxreddit</a></li>`
    );

    vxredditButton.on("click", () => {
      // copy the link to clipboard
      const vxredditLink = `https://www.vxreddit.com${thingLinkHref}`;
      navigator.clipboard.writeText(vxredditLink).then(() => {
        // alert the user that the link has been copied
        alert("vxreddit link copied to clipboard!");
      });
    });

    const rxdditButton = $(
      `<li><a href="javascript:;" class="xreddit-button">rxddit</a></li>`
    );

    rxdditButton.on("click", () => {
      // copy the link to clipboard
      const rxdditLink = `https://www.rxddit.com${thingLinkHref}`;
      navigator.clipboard.writeText(rxdditLink).then(() => {
        // alert the user that the link has been copied
        alert("rxddit link copied to clipboard!");
      });
    });

    buttonList.append(vxredditButton);
    buttonList.append(rxdditButton);
  });
};

// initial call to add buttons to existing posts
addXRedditButtons();
setupMorePostsObserver(() => {
  // when new posts are loaded
  addXRedditButtons();
});