//js正則實現用戶輸入銀行卡號的控制及格式化

<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">