asp.net+jquery滚动滚动条加载数据的下拉控件

$.ajax({ 
type: options.getMethod, 
url: options.jsonUrl, 
data: params, 
success: function(data){ 
if(isScroll) 
$.CreateListItem(showbox,data,options); 
else 
$.CreateBox(showbox,data,options); 
}, 
complete:function(){ }, 
error:function(e){ 
$(options.loadBox).css('background-image','none'); 
$(options.loadBox).append('<span>data connect error!'+e+'</span>'); 
}

$(showbox).scroll(function(){ 
if(options.total==$(this).children("ul").children("li").length) 
return; 
var scrolltop=$(showbox).attr('scrollTop'); 
var scrollheight=$(showbox).attr('scrollHeight'); 
var windowheight=$(showbox).attr('clientHeight'); 
var scrolloffset=20; 
$(options.loadBox).css('top',scrolltop); 
if(scrolltop>=(scrollheight-(windowheight+scrolloffset))&&!loading) 
{ 
loading=true; 
$(options.loadBox).show(); 
options.total=$(this).children("ul").children("li").length; 
$.WebComboGetData(showbox,options,true); 
} 
});