js 格式化银行卡号

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;
}