initIntersectionObserver

gistfile1.txt

const initIntersectionObserver = () => {
  const options = {
  	/* root: document.querySelector(".cat-list") */
  }

  const callback = entries => {
    entries.forEach(entry => {
      if (entry.target.id === 'cat-tile-0') {
        topSentCallback(entry);
      } else if (entry.target.id === `cat-tile-${listSize - 1}`) {
        botSentCallback(entry);
      }
    });
  }

  var observer = new IntersectionObserver(callback, options);
  observer.observe(document.querySelector("#cat-tile-0"));
  observer.observe(document.querySelector(`#cat-tile-${listSize - 1}`));
}