js瀑布流

<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>无标题文档</title>
<style>
*{
   margin: 0;
   padding: 0;
   list-style: none;
}
#box {
   margin: 0 auto;
   966px;
   overflow: hidden;
}

#box ul {
   300px;
   height: auto;
   float:left;
   margin-right: 20px;
   border: #000 1px solid;
}

#box ul li {
   280px;
   border: #999 1px solid;
   margin: 10px 9px;
}
</style>
<script>
function rnd(n,m){
   return parseInt(Math.random() * (m - n) + n);
}
function createLi(){
   var oLi = document.createElement('li');
   oLi.style.height = rnd(50,300) + 'px';
   oLi.style.background = 'rgb('+rnd(0,256)+','+rnd(0,256)+','+rnd(0,256)+')';
   return oLi;
}
window.onload = function(){
   var oBox = document.getElementById('box');
   var aUl = oBox.children;

   function appendLi(){
       for(var i = 0; i < 15; i++){
       var oLi = createLi();
       var iMinUl;
       var arrUl = [];
       for(var j = 0; j < aUl.length; j++){
           arrUl[j] = aUl[j];
       }
       arrUl.sort(function(n1,n2){
           return n1.offsetHeight - n2.offsetHeight;
       });
           arrUl[0].appendChild(oLi);
       }
   }
   appendLi();
   window.onscroll = function(){
       var oScroll = document.documentElement.scrollTop || document.body.scrollTop;
       var clientH = document.documentElement.clientHeight;
       var oBoxh = oBox.scrollHeight;
       if(oScroll + clientH >= oBoxh){
           appendLi();
       }
   }
}
</script>
</head>

<body>
<div id="box">
   <ul></ul>
    <ul></ul>
    <ul></ul>
</div>
</body>
</html>