不管页面内容是不是占满一屏，footer都保持在最底部

直接上代码：

<style>
*{ margin:0; padding:0}
#container{background:#33CCFF}
#footer{background:#FFCC00;width:100%;}
</style>
<div id="container"> 5416416410</div>
<div id="footer">bottom</div>
<script language="JavaScript" type="text/javascript">
function test(){
var infoHeight = document.getElementById("container").scrollHeight;
var bottomHeight = document.getElementById("footer").scrollHeight;
var allHeight = document.documentElement.clientHeight;

var bottom = document.getElementById("footer");
if((infoHeight + bottomHeight) < allHeight){
bottom.style.position = "absolute";
bottom.style.bottom = "0";
}else{
bottom.style.position = "";
bottom.style.bottom = "";
}

setTimeout(function(){test();},10);
}
test();
</script>