复制代码 代码如下:
/** event handler for mouse wheel event.
         *鼠标滚动事件
         */ 
        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) { 
                /** mozilla case. */ 
                /** in mozilla, sign of delta is different than in ie.
                 * also, delta is multiple of 3.
                 */ 
                delta = -event.detail / 3; 
            } 
            /** if delta is nonzero, handle it.
             * basically, delta is now positive if wheel was scrolled up,
             * and negative, if wheel was scrolled down.
             */ 
            if (delta) 
                handle(delta); 
            /** prevent default actions caused by mouse wheel.
             * that might be ugly, but we handle scrolls somehow
             * anyway, so don't bother here..
             */ 
            if (event.preventdefault) 
                event.preventdefault(); 
            event.returnvalue = false; 
        }
/** initialization code. 
         * if you use your own event management code, change it as required.
         */ 
        if (window.addeventlistener) { 
            /** dommousescroll is for mozilla. */ 
            window.addeventlistener('dommousescroll', wheel, false); 
        } 
        /** ie/opera. */ 
        window.onmousewheel = document.onmousewheel = wheel;
/** this is high-level function.
         * it must react to delta being more/less than zero.
         */ 
        var handle = function(delta) { 
            var random_num = math.floor((math.random() * 100) + 50); 
            if (delta                 // 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; 
            } 
        }