<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;i<account.length;i++){        accountChar = account.substr (i,1);        if (!isNaN (accountChar) && (accountChar != " ")) accountNumeric = accountNumeric + accountChar;      }      account = "";      for (i=0;i<accountNumeric.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">