滚轮事件 & 视窗问题

//一般浏览器
obj.onmousescroll = function(){
   blablablabla; 
};
//火狐浏览器
document.addEventListener(‘DOMMouseScroll‘,function(){
    blablablabal;
},false);

if ( navigator.userAgent.indexOf(‘MSIE‘) >= 0 ){
    var total = document.body.offsetHeight;
    var view = document.documentElement.clientHeight;
    var top = document.documentElement.scrollTop;
} else {
    var total = document.documentElement.offsetHeight;
    var view = document.documentElement.clientHeight;
    var top = document.body.scrollTop || document.documentElement.scrollTop;
}