隨機產生指定位元的驗證碼

：

隨機產生指定位元的驗證碼的代碼如下：
<script language="javascript">
function checkCode(digit){
 //自動產生驗證碼
 var result="";
 for(i=0;i<parseInt(digit);i++){
  result=result+(parseInt(Math.random()*10)).toString();
 }
 return result;
}
</script>
<script language="javascript">
function deal(){
 result.innerHTML="&nbsp;&nbsp;產生的驗證碼："+checkCode(form1.digit.value);
}
</script>
 

<body>
<form name="form1" method="post" action="">
<table width="271" height="178"  border="0" cellpadding="0" cellspacing="0" background="image/result.gif">
  <tr>
    <td valign="top"><table width="100%" height="150"  border="0" cellpadding="0" cellspacing="0">
      <tr>
        <td width="15%" height="55">&nbsp;</td>
        <td width="69%" valign="bottom"><div id="result">&nbsp;&nbsp;產生的驗證碼：</div></td>
        <td width="16%">&nbsp;</td>
      </tr>
      <tr>
        <td height="68">&nbsp;</td>
        <td align="center">
            <br>
            請輸入要產生的驗證碼的位元：<br>
            <br>
            <input name="digit" type="text" class="wenbenkuang" id="digit" value="4">
            (1-15)</td>
        <td>&nbsp;</td>
      </tr>
      <tr>
        <td>&nbsp;</td>
        <td align="center"><input name="Submit" type="button" class="go-wenbenkuang" value="產生" onClick="deal()">
          &nbsp;
          <input name="Submit2" type="button" class="go-wenbenkuang" value="重新整理" onClick="window.location.reload();"></td>
        <td>&nbsp;</td>
      </tr>
    </table></td>
  </tr>
</table>
</form>
</body>