In the withinElement function used by mouseenter and mouseleave events try..catch statement is placed inside the while loop, where its task is to break the loop. So, why not place the loop inside the try..catch and let the exception stop the looping?

try {

while(parent && parent !== this){

parent = parent.parentNode;

}

} catch(e){

parent = this; // for jQuery 1.3.2 behavior. In jQuery 1.4 nightly, just skip this line

}