User blog comment:Kirkburn/Technical Update: April 27, 2015/@comment-4403232-20150428104421/@comment-452-20150428141824

Thanks, that confirms that it's definitely not just a rwby issue, so it must have been due to something about this week's update.

Good news: I found the cause, and it IS the sharing buttons.

The javascript for this toggler is a poorly written mess, so I would advise finding an alternate solution.

edit: why is it a "poorly written mess", why what does this have to do with the sharing buttons?

The script makes a list of literally all the elements on a page, with: elems = document.getElementsByTagName("*"); On the test page I'm looking at, that's 1524 elements. Then it loops through them, checking each of them for the presence of a toggler class.

It worked, but that's like ...calling every phone number sequentially instead of using a phonebook/google. It's just plain dumb.

The new sharing buttons have a "class" object associated with them, and this script is trying to access that object as if it's a normal class attribute, which it is not, which causes the error "Uncaught TypeError: undefined is not a function", because className is a object, not a string.

While it's a little abnormal that the sharing buttons use the (normally reserved) name "class" for an object, it wouldn't be a problem by itself.