User blog comment:Dopp/Technical Update: November 29, 2011/@comment-3235402-20111205135159/@comment-1066636-20111209125410

That's not really Wikia's fault - the Common.js on that wiki is referencing a function which doesn't exist ("hasClass"). Someone either deleted that function or didn't copy it along with the "collapsible tables" code in the first place.

The missing function causes a JavaScript error which in turn causes other scripts to cease working. Simply put, there's nothing wrong with Wikia's code, the custom code on that wiki is responsible.