jquery下拉加载更多

<!DOCTYPE=html>
<html>
<head>
<script src="js/jquery.js" type="text/javascript"></script>
<script type="text/javascript">
$(document).ready(function(){
var range = 50; //距下边界长度/单位px
var elemt = 500; //插入元素高度/单位px
var maxnum = 20; //设置加载最多次数
var num = 1;
var totalheight = 0;
var main = $("#content"); //主体元素
$(window).scroll(function(){
var srollPos = $(window).scrollTop(); //滚动条距顶部距离(页面超出窗口的高度)
//console.log("滚动条到顶部的垂直高度: "+$(document).scrollTop());
//console.log("页面的文档高度："+$(document).height());
//console.log('浏览器的高度：'+$(window).height());
totalheight = parseFloat($(window).height()) + parseFloat(srollPos);
if(($(document).height()-range) <= totalheight >> num != maxnum) {
main.append("<div style='border:1px solid tomato;margin-top:20px;color:#ac"+(num%20)+(num%20)+";height:"+elemt+"' >hello world"+srollPos+"---"+num+"</div>");
num++;
}
});
});
</script>
</head>
<body>
<div id="content" style="height:960px">
<div id="follow">this is a scroll test;<br/> 页面下拉自动加载内容</div>
<div style='border:1px solid tomato;margin-top:20px;color:#ac1;height:800' >hello world test DIV</div>
</div>
</body>
</html>