大家都知道，固定定位对于低版本浏览器不兼容，如何解决，看下边方案。
<style>
*{
margin:0;
padding:0;
}
.box{
width:200px;
height:200px;
background:red;
position:absolute;
right:0;
bottom:0;
}
body{
height:2000px;
}
</style>
<body>
<div class="box">
</div>
</body>
<script>
var box = document.getElementsByClassName('box')[0];
window.onload = window.onscroll = function () {
var sct = document.documentElement.scrollTop || document.body.scrollTop;
box.style.top = sct-box.offsetHeight+document.documentElement.clientHeight+'px'
}
</script>
