鼠标滑轮事件监听，兼容各类浏览器

/***********************
        * 函数：判断滚轮滚动方向
        * 作者：gc
        * 参数：dom对象 callback回调函数
        * 返回：滚轮方向 1：向上 -1：向下
        regScroll(document.getElementById("dituContent"));
        *************************/
       regScroll(document.getElementById("dituContent"));
       function regScroll(dom,callbackUp,callbackDown) {
           var scrollFunc = function (e) {
               e = e || window.event;
               if (e.wheelDelta) {//IE/Opera/Chrome
                   if (e.wheelDelta == 120) {
                      callbackUp();
                       return 1;
                   } else {
                      callbackDown();
                       return -1;
                   }
               } else if (e.detail) {//Firefox
                   if (e.detail == -3) {
                      callbackUp();
                       return 1;
                   } else {
                       callbackDown();
                       return -1;
                   }
               }
           }
           /*注册事件*/
           if (dom.addEventListener) {
               dom.addEventListener('DOMMouseScroll', scrollFunc, false);
           }//W3C
           dom.onmousewheel = scrollFunc;//IE/Opera/Chrome/Safari
       }