js正则实现用户输入银行卡号的控制及格式化

//js正则实现用户输入银行卡号的控制及格式化
<script language="javascript" type="text/javascript">
function formatBankNo (BankNo){
    if (BankNo.value == "") return;
    var account = new String (BankNo.value);
    account = account.substring(0,22); /*帐号的总数, 包括空格在内 */
    if (account.match (".[0-9]{4}-[0-9]{4}-[0-9]{4}-[0-9]{7}") == null){
        /* 对照格式 */
        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++){    /* 可将以下空格改为-,效果也不错 */
                if (i == 4) account = account + " "; /* 帐号第四位数后加空格 */
                if (i == 8) account = account + " "; /* 帐号第八位数后加空格 */
                if (i == 12) account = account + " ";/* 帐号第十二位后数后加空格 */
                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">