JavaScript 实现网页随机超链接地址生成

<html>
<head>
<title>在网页上随机产生超链接地址</title>
<script language="javascript">
<!--
  url = new Array();
  url[0] = "http://www.yahoo.com";
  url[1] = "https://www.jb51.net";
  url[2] = "http://www.baidu.com";
  i = Math.random() * url.length;
  i = Math.floor(i);
  str = "<a id='linkID' href='" + url[i] + "'>";
-->
</script>
</head>
<body>
<script language="javascript">
<!--
  document.write(str + "本链接是随机产生的，刷新页面会更换。</a><br>");
  document.write(linkID.href);
//-->
</script>
</body>
</html>