var className="aaa-" + Math.floor(Math.random()*9+1) ;
document.body.className = className;
追问
怎么还是实现不了
追答<body class="t-pattern-1">
123
</dody>
<script language="javascript">
var className="t-pattern-" + Math.floor(Math.random()*6+1) ;
document.body.className = className;
</SCRIPT>