<script language="javascript" type="text/javascript">
var Body=document.compatMode!="BackCompat" ? document.documentElement: document.body;
document.write(new Array(0).join("<br>")) //new Array(10).join("<br>")
var init_pos=last_pos=document.getElementById("你的loading层ID").style.top
setInterval(function scrollit(){
target_pos=Body.scrollTop+init_pos
step=(target_pos-last_pos)/1|0
document.getElementById("你的loading层ID").style.top+=step 
last_pos+=step 
},1)
</script>