This appears to be happening on my system because almFadeIn is trying to set opacity on an array of 1 element, rather than an element.
That’s happening because almDomParser is returning an array.
(Array.prototype.slice.call(data.body.childNodes) returns an array with one node in it.)
And that’s happening because of this code:
if (!alm.transition_container) { // No transition container
alm.el = alm.html;
reveal = (alm.container_type === ‘table’) ? almTableWrap(alm.html) : almDomParser(alm.html, ‘text/html’);
almTableWrap appears to deliberately return an array, so I assume reveal is meant to contain an array… Except everywhere else in that code, reveal is treated as a single element (not an array).
Very strange.