我的为啥移不动？
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>jQuery动画特效</title>
</head>
<body>
<input id="btnleft" type="button" value="左移" >
<input id="btnright" type="button" value="右移" >
<div style="background-color:red;width:100px;height:100px;position:absolute;top:50px"></div>
<script type="text/javascript">
$(function(){
$("#btnleft").bind("click",function(){
$("div").animate({left:"-=50px"},2000,function(){
alert("左移成功");
})
})
$("#btnright").bind("click",function(){
$("div").animate({left:"+=50px"},2000,function(){
alert("右移成功");
})
})
});
</script>
</body>
</html>
