Using svn jquery, testcase is here: ​http://fuzz.bassistance.de/jQueryFormValidation/parentsBug.html Problem occurs in both FF1.5 and IE6.

My research of the problem is this: In line 873 (var t = axis[i];), undefined is assigned to t. Why that? The assignments in axis for parents and ancestors both refer to jQuery.parents. jQuery.parents on the other hand is defined somewhere later. I did a quick test and defined that function directly in the axis object, that works. Seems to be a 'reference to a not yet defined element' problem. I tried changing the reference to a string, but that causes other errors...

​http://msdn.microsoft.com/workshop/author/dhtml/reference/objects/currentstyle.asp

  else if (e.currentStyle) { 
     p = p.replace(/-(w)/g,function(m,c){return c.toUpperCase()}); 
     r = e.currentStyle[p]; 
  } 

​http://www.nabble.com/Re%3A-%24%28foo%29.css%28%27min-height%27%29-bug--p5427663.html

The current code in the base only gives back an normale object instead of the handy methods...

The old code:

return i == null ? this.cur : this.cur[i];

replaces by:

return i == null ? $(this.cur) : $(this.cur[i]);

seem to work fine.