JavaScript: Cancel Event Bubbling

Another common tidbit of JavaScript code:

Cancel event bubbling:

function stopEvent(evt){
evt = evt || window.event;
if (evt.stopPropagation){
evt.stopPropagation();
evt.preventDefault();
}else if(typeof evt.cancelBubble != "undefined"){
evt.cancelBubble = true;
evt.returnValue = false;
}
return false;
}