封装鼠标滚轮事件，兼容方法。。。拿去用吧

 var addEvent = (function(window, undefined) {
        var _eventCompat = function(event) {
            var type = event.type;
            if (type == 'DOMMouseScroll' || type == 'mousewheel') {
                event.delta = (event.wheelDelta) ? event.wheelDelta / 120 : -(event.detail || 0) / 3;
            }
            //alert(event.delta);
            if (event.srcElement && !event.target) {
                event.target = event.srcElement;
            }
            if (!event.preventDefault && event.returnValue !== undefined) {
                event.preventDefault = function() {
                    event.returnValue = false;
                };
            }
            /*......其他一些兼容性处理 */
            return event;
        };
        if (window.addEventListener) {
            return function(el, type, fn, capture) {
                if (type === "mousewheel" && document.mozHidden !== undefined) {
                    type = "DOMMouseScroll";
                }
                el.addEventListener(type, function(event) {
                    fn.call(this, _eventCompat(event));
                }, capture || false);
            }
        } else if (window.attachEvent) {
            return function(el, type, fn, capture) {
                el.attachEvent("on" + type, function(event) {
                    event = event || window.event;
                    fn.call(el, _eventCompat(event));
                });
            }
        }
        return function() {};
    })(window);

封装得滚轮事件，兼容方法。。。拿去用吧