function handle(delta) {
if (delta < 0)
/* um evento que deseje */;
else
/* um evento que deseje */;
}
function wheel(event){
var delta = 0;
if (!event) event = window.event;
if (event.wheelDelta) {
delta = event.wheelDelta/120;
if (window.opera) delta = -delta;
} else if (event.detail) {
delta = -event.detail/3;
}
if (delta)
handle(delta);
if (event.preventDefault)
event.preventDefault();
event.returnValue = false;
}
if(window.addEventListener)
window.addEventListener('DOMMouseScroll', wheel, false);
window.onmousewheel = document.onmousewheel = wheel;