java如何生成订单号 js生成订单号

*********前台显示框****************
  <input type="text" id="WIDout_trade_no" name="WIDout_trade_no" />
**************js代码*****************
<script language="javascript">
 function GetDateNow()
    {
        var vNow = new Date();
        sNow += String(vNow.getFullYear());
        sNow += String(vNow.getMonth() + 1);
        sNow += String(vNow.getDate());
       sNow += String(vNow.getHours());
        sNow += String(vNow.getMinutes());
        sNow += String(vNow.getSeconds());
        sNow += String(vNow.getMilliseconds());
        document.getElementById("WIDout_trade_no").value = sNow;
    }    GetDateNow();
</script>