User blog comment:DaNASCAT/Technical Update: October 11, 2011/@comment-1066636-20111015213605

Not sure whether it's been introduced with this update, but I've been getting a "s is undefined" JS error lately on all Wikia wikis (FF7.0.1) which is a tad annoying as it'll randomly stop other scripts from working.

Apparently it originates from: function simpleHash(s, tableSize) { var i, hash = 0; for (i = 0; i < s.length; i++) { The "for" line triggers the error.