js 动态创建 html元素

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 
<html xmlns="http://www.w3.org/1999/xhtml"> 
<head> 
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" /> 
<title> js学习之动态创建html元素</title> 
<style></style><style bogus="1">body{margin:0;padding:0;} 
.sky{background:#000;width:1000;height:500px; position:relative;} 
#s{ background:#FFF; width:1px; height:1px; overflow:hidden; position:absolute;}</style> 
</head>

<body> 
 
<button id="creatstar" onclick="creatstars()">没事造星星玩</button> 
<script type="text/javascript"><!-- 
function $(id){ return document.getElementById(id);};

function creatstars(){ 
var star = document.createElement("div"); 
star.id = "s"; 
var posX = Math.floor(Math.random(star.style.top)*400+100); 
var posY = Math.floor(Math.random(star.style.left)*1000+1); 
$("sky").appendChild(star); 
star.style.top = posX + "px"; 
star.style.left = posY + "px"; 
} 
// --></script> 
</body> 
</html>

[Ctrl+A 全选注:如需引入外部Js需刷新才能执行]