nitter/public/js/infiniteScroll.js

// @license http://www.gnu.org/licenses/agpl-3.0.html AGPL-3.0
// SPDX-License-Identifier: AGPL-3.0-only
function insertBeforeLast(node, elem) {
  node.insertBefore(elem, node.childNodes[node.childNodes.length - 2]);
}

function getLoadMore(doc) {
  return doc.querySelector(".show-more:not(.timeline-item)");
}

function isDuplicate(item, itemClass) {
  const tweet = item.querySelector(".tweet-link");
  if (tweet == null) return false;
  const href = tweet.getAttribute("href");
  return (
    document.querySelector(itemClass + " .tweet-link[href='" + href + "']") !=
    null
  );
}

window.onload = function () {
  const url = window.location.pathname;
  const isTweet = url.indexOf("/status/") !== -1;
  const containerClass = isTweet ? ".replies" : ".timeline";
  const itemClass = containerClass + " > div:not(.top-ref)";

  var html = document.querySelector("html");
  var container = document.querySelector(containerClass);
  var loading = false;

  function handleScroll(failed) {
    if (loading) return;

    if (html.scrollTop + html.clientHeight >= html.scrollHeight - 3000) {
      loading = true;
      var loadMore = getLoadMore(document);
      if (loadMore == null) return;

      loadMore.children[0].text = "Loading...";

      var url = new URL(loadMore.children[0].href);
      url.searchParams.append("scroll", "true");

      fetch(url.toString())
        .then(function (response) {
          if (response.status > 299) throw "error";
          return response.text();
        })
        .then(function (html) {
          var parser = new DOMParser();
          var doc = parser.parseFromString(html, "text/html");
          loadMore.remove();

          for (var item of doc.querySelectorAll(itemClass)) {
            if (item.className == "timeline-item show-more") continue;
            if (isDuplicate(item, itemClass)) continue;
            if (isTweet) container.appendChild(item);
            else insertBeforeLast(container, item);
          }

          loading = false;
          const newLoadMore = getLoadMore(doc);
          if (newLoadMore == null) return;
          if (isTweet) container.appendChild(newLoadMore);
          else insertBeforeLast(container, newLoadMore);
        })
        .catch(function (err) {
          console.warn("Something went wrong.", err);
          if (failed > 3) {
            loadMore.children[0].text = "Error";
            return;
          }

          loading = false;
          handleScroll((failed || 0) + 1);
        });
    }
  }

  window.addEventListener("scroll", () => handleScroll());
};
// @license-end