鼠标滚动事件

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<title>无标题文档</title>

</head>

<body>

</body>

</html>

var wheel = function(event) {
            var delta = 0;
            if (!event) /* For IE. */
                event = window.event;
            if (event.wheelDelta) { /* IE/Opera. */
                delta = event.wheelDelta / 120;
           } else if (event.detail) {

         delta = -event.detail / 3;
            }

            if (delta)
                handle(delta);

           if (event.preventDefault)
               event.preventDefault();
           event.returnValue = false;
      }

    if (window.addEventListener) {
            /** DOMMouseScroll is for mozilla. */
            window.addEventListener('DOMMouseScroll', wheel, false);
        }
        /** IE/Opera. */
        window.onmousewheel = document.onmousewheel = wheel;
      var handle = function(delta) {
            var random_num = Math.floor((Math.random() * 100) + 50);
            if (delta < 0) {
                alert("鼠标滑轮向下滚动：" + delta + "次！"); // 1
               // $("btn_next_pic").onclick(random_num);
               return;
            } else {
                alert("鼠标滑轮向上滚动：" + delta + "次！"); // -1
               // $("btn_last_pic").onclick(random_num);
               return;
            }
        }

</script>