Basically there are two event models in javascript. Event capturing and Event bubbling. In event bubbling, if you click on inside div, the inside div click event fired first and then the outer div click fired. while in event capturing, first the outer div event fired and than the inner div event fired. To stop event propagation, use this code in your click method.
if (!e) var e = window.event;
e.cancelBubble = true;
if (e.stopPropagation) e.stopPropagation();