请大神帮我看下这个代码为什么动不起来
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>js动画制作</title>
</head>
<style>
body,div,span{
margin:0;
padding:0;
}
#div1{
height: 200px;
width: 200px;
background-color: #333;
position: relative;
left: -200px;
top: 0;
}
#div1 span{
height:50px;
width:20px;
background-color:#666;
position: absolute;
left:200px;
top:75px;
}
</style>
<script>
window.onload = function(){
var oDiv = document.getElementById('div1');
oDiv.onmouseover = function(){
startMove(0);
}
oDiv.onmouseout = function(){
startMove(-200);
}
}
var timer = null;
function startMove(iTarget){
clearInterval(timer);
var oDiv = document.getElementById('div1');
timer = setInterval(function(){
var speed=0;
if(oDiv.offsetLeft<iTaget){speed = 10;}
else{speed = -10;}
if(oDiv.offsetLeft == iTarget){
clearInterval(timer);
}
else{
oDiv.style.left = oDiv.offsetLeft+ speed +'px';
}
},30)
}
</script>
<body>
<div id="div1"><span id="share">分享</span></div>
</body>
</html>
