Presumably website changed, jumpCols empty

[maradude]

Hey,

Seems that the current html for mangadex has changed and jumpCols can't find anything. I got the script's basic functionality back up and running but I didn't check if I broke anything else as I didn't read the rest of your source code or know what the app looked like before I made these changes.

  const content = document.querySelector('#content');
  const userBtns = content.querySelectorAll('.col-md-4')[0]; // selects comment, report, settings buttons
  const jumpCols = content.querySelectorAll('.col-md-3');
  const mangaLink = content.querySelectorAll('.panel-title')[0].querySelector('a'); // selects title
...
  userBtns.classList.replace('col-md-4', 'col-md-3'); // smaller button group
  jumpCols[1].classList.replace('col-md-3', 'col-md-2'); // smaller group choice, maybe a bit too small
  jumpCols[0].parentNode.appendChild(newCol);

As I didn't actually read most of your source code or know much about javascript in general, I don't fell comfortable sending a pull request, but if you're still working on this then here's what I found was broken.

Cheers for the great script and sorry to bother if this project was already dead.