原理：window/document对象的mousewheel事件

var scrollFunc = function (e) {    
var direct = 0;    
e = e || window.event;    
if (e.wheelDelta) {  
//判断浏览器IE，谷歌滑轮事件        
if (e.wheelDelta > 0) { //当滑轮向上滚动时            
console.log("滑轮向上滚动");        
}       
 if (e.wheelDelta < 0) { //当滑轮向下滚动时           
console.log("滑轮向下滚动");        }    
} 
else if (e.detail) {  //Firefox滑轮事件       
 if (e.detail> 0) { //当滑轮向上滚动时            
console.log("滑轮向上滚动");        }        
if (e.detail< 0) { //当滑轮向下滚动时            
console.log("滑轮向下滚动");        }   
 }
};
//给页面绑定滑轮滚动事件if (document.addEventListener) {
    document.addEventListener('DOMMouseScroll', scrollFunc, false);
}
//滚动滑轮触发scrollFunc方法
window.onmousewheel = document.onmousewheel = scrollFunc;