jq-animate实现返回顶部效果：
<!doctype html>
<html lang="en">
<head>
<meta charset="UTF-8" />
<title>jq-animate回到顶部</title>
<style type="text/css">
* {
margin: 0;
padding: 0;
}
#wrap {
height: 30000px;
}
#toTop {
height: 50px;
50px;
font-size: 30px;
line-height: 50px;
text-align: center;
position: fixed;
right: 10px;
bottom: 10px;
}
</style>
<script src="js/jquery-1.8.3.js" type="text/javascript" charset="utf-8"></script>
</head>
<body>
<div id="wrap">
<button id="toTop">^</button>
</div>
<script type="text/javascript">
$('#toTop').click(function() {
var top1 = $('body').scrollTop();
var top2 = $(document).scrollTop();//document对象不能执行animate
var top3 = $(window).scrollTop();//window对象不能执行animate
console.log(top1);
console.log(top2);
console.log(top3);
$('body').animate({
scrollTop: '0'
},1000);
});
</script>
</body>
</html>