script language="javascript" type="text/javascript">
function formatBankNo (BankNo){
  if (BankNo.value == "") return;
  var account = new String (BankNo.value);
  account = account.substring(0,22); /*帳號的總數, 包括空格在內 */
  if (account.match (".[0-9]{4}-[0-9]{4}-[0-9]{4}-[0-9]{7}") == null){
    /* 對照格式 */
    if (account.match (".[0-9]{4}-[0-9]{4}-[0-9]{4}-[0-9]{7}|" + ".[0-9]{4}-[0-9]{4}-[0-9]{4}-[0-9]{7}|" +
    ".[0-9]{4}-[0-9]{4}-[0-9]{4}-[0-9]{7}|" + ".[0-9]{4}-[0-9]{4}-[0-9]{4}-[0-9]{7}") == null){
      var accountNumeric = accountChar = "", i;
      for (i=0;iaccount.length;i++){
        accountChar = account.substr (i,1);
        if (!isNaN (accountChar)  (accountChar != " ")) accountNumeric = accountNumeric + accountChar;
      }
      account = "";
      for (i=0;iaccountNumeric.length;i++){  /* 可將以下空格改為-,效果也不錯 */
        if (i == 4) account = account + " "; /* 帳號第四位數后加空格 */
        if (i == 8) account = account + " "; /* 帳號第八位數后加空格 */
        if (i == 12) account = account + " ";/* 帳號第十二位后數后加空格 */
        account = account + accountNumeric.substr (i,1)
      }
    }
  }
  else
  {
    account = " " + account.substring (1,5) + " " + account.substring (6,10) + " " + account.substring (14,18) + "-" + account.substring(18,25);
  }
  if (account != BankNo.value) BankNo.value = account;
}
/script>

input type="text" value="" size="25" onkeyup="formatBankNo(this)" onkeydown="formatBankNo(this)" name="account" id="account">