Javascript: IE Error, Firebug not erring. Where is it?

Again, I am working with code from my predecessor and am at a loss for this one. It appears to be a sampled navigation script. It is receiving an error in IE stating Object doesn't support this property or method. Here is what I have narrowed the error down to.

The function:

/**
* hoverIntent r5 // 2007.03.27 // jQuery 1.1.2+
* <http://cherne.net/brian/resources/jquery.hoverIntent.html>
* 
* @param  f  onMouseOver function || An object with configuration options
* @param  g  onMouseOut function  || Nothing (use configuration options object)
* @author    Brian Cherne <brian@cherne.net>
*/
(function($){$.fn.hoverIntent=function(f,g){var cfg={sensitivity:7,interval:100,timeout:0};
cfg=$.extend(cfg,g?{over:f,out:g}:f);
var cX,cY,pX,pY;
var track=function(ev){cX=ev.pageX;
cY=ev.pageY;
};
var compare=function(ev,ob){ob.hoverIntent_t=clearTimeout(ob.hoverIntent_t);
if((Math.abs(pX-cX)+Math.abs(pY-cY))<cfg.sensitivity){$(ob).unbind("mousemove",track);
ob.hoverIntent_s=1;
return cfg.over.apply(ob,[ev]);
}else{pX=cX;
pY=cY;
ob.hoverIntent_t=setTimeout(function(){compare(ev,ob);
},cfg.interval);
}};
var delay=function(ev,ob){ob.hoverIntent_t=clearTimeout(ob.hoverIntent_t);
ob.hoverIntent_s=0;
return cfg.out.apply(ob,[ev]);
};
var handleHover=function(e){var p=(e.type=="mouseover"?e.fromElement:e.toElement)||e.relatedTarget;
while(p&&p!=this){try{p=p.parentNode;
}catch(e){p=this;
}}if(p==this){return false;
}var ev=jQuery.extend({},e);
var ob=this;
if(ob.hoverIntent_t){ob.hoverIntent_t=clearTimeout(ob.hoverIntent_t);
}if(e.type=="mouseover"){pX=ev.pageX;
pY=ev.pageY;
$(ob).bind("mousemove",track);
if(ob.hoverIntent_s!=1){ob.hoverIntent_t=setTimeout(function(){compare(ev,ob);
},cfg.interval);
}}else{$(ob).unbind("mousemove",track);
if(ob.hoverIntent_s==1){ob.hoverIntent_t=setTimeout(function(){delay(ev,ob);
},cfg.timeout);
}}};
return this.mouseover(handleHover).mouseout(handleHover);
};
})(jQuery);

The document.ready line triggering the error:

var config = {    
         sensitivity: 1, // number = sensitivity threshold (must be 1 or higher)    
         interval: 50, // number = milliseconds for onMouseOver polling interval    
         over: megaHoverOver, // function = onMouseOver callback (REQUIRED)    
         timeout: 200, // number = milliseconds delay before onMouseOut    开发者_运维百科
         out: megaHoverOut // function = onMouseOut callback (REQUIRED)    
    };

    $("ul#topnav li .sub").css({'opacity':'0'});
    $("ul#topnav li").hoverIntent(config);

I am at a loss as to how to resolve this and finally get this section fixed.

The two functions that are defined within document.ready.

function megaHoverOver(){
        $(this).find(".sub").stop().fadeTo('fast', 1).show();

        //Calculate width of all ul's
        (function($) { 
            jQuery.fn.calcSubWidth = function() {
                rowWidth = 0;
                //Calculate row
                $(this).find("ul").each(function() {                    
                    rowWidth += $(this).width(); 
                }); 
            };
        })(jQuery); 

        if ( $(this).find(".row").length > 0 ) { //If row exists...
            var biggestRow = 0; 
            //Calculate each row
            $(this).find(".row").each(function() {                             
                $(this).calcSubWidth();
                //Find biggest row
                if(rowWidth > biggestRow) {
                    biggestRow = rowWidth;
                }
            });
            //Set width
            $(this).find(".sub").css({'width' :biggestRow});
            $(this).find(".row:last").css({'margin':'0'});

        } else { //If row does not exist...

            $(this).calcSubWidth();
            //Set Width
            $(this).find(".sub").css({'width' : rowWidth});

        }
    }

    function megaHoverOut(){ 
      $(this).find(".sub").stop().fadeTo('fast', 0, function() {
          $(this).hide(); 
      });
    }

---

I'm able to run that code without errors (see http://jsfiddle.net/veHEY/). It looks like the issue might be in the megaHoverOver and megaHoverOut functions that you're passing in through the configuration object. Do you have the code for those functions?

---

Previously:

The problem is almost certainly opacity, which is not supported in IE. Check out this nice quirksmode article on cross-browser opacity issues.

Correction: As @patrick rightly points out, and backs up with a source code reference to boot, jQuery is smart enough to automatically deal with IE's own special brands of opacity handling. Whatever the OP's problem is, this is not the answer.