为js取不到html图片当前的值

Question

结果都是为空 求高手看看 下面是代码 
就是想去图片的top的值<ul>
<li><img style="position:absolute;top:0px;" src="1.png" id="div1"/><a id="A" style="position:absolute;" onmouseOver="mouseOver(1)" onmouseOut="mouseOut(1)">A</a></li>
<li><img style="position:absolute;top:0px;" src="1.png" id="div2"/><a id="B" style="position:absolute;" onmouseOver="mouseOver(2)" onmouseOut="mouseOut(2)">B</a></li> 
</ul><script type="text/javascript">
function mouseOver(u){
var a=0;
var o=document.getElementById('div'+u);
function move(){ a++; 
if(a==29){
var t=u.offsetTop;
while(u=u.offsetParent){
t+=u.offsetTop;
}
alert("当前图片高度为："+t);
clearInterval(time);
}
o.style.top = (o.style.top.replace('px','')-0 +5);}
var time = window.setInterval(move,1);}
function mouseOut(u){
setTimeout(function(){
var ab=0; 
var o=document.getElementById('div'+u);
function mov(){ ab++;
if(ab==29){clearInterval(time);}
o.style.top = (o.style.top.replace('px','') - 5);}
var time = window.setInterval(mov,1);},500);}
</script>