js实现模拟银行卡账号输入显示效果

<script language="javascript" type="text/javascript">function www_jb51_net (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;}function checkBankNo (BankNo){if (BankNo.value == "") return;if (BankNo.value.match (".[0-9]{4}-[0-9]{4}-[0-9]{4}-[0-9]{7}") == null){if (BankNo.value.match ("[0-9]{19}") != null)www_jb51_net (BankNo)}}function checkEnterForFindListing(e){var characterCode;if(e && e.which){e = e;characterCode = e.which ;}else{e = event;characterCode = e.keyCode;}if(characterCode == 22){document.forms[getNetuiTagName("findListingForm")].submit();return false;}else{return true ;}}</script>只能输入数字，并且每输入4位数字会增加一个 - <br /><input type="text" value="" size="25" onkeyup="www_jb51_net(this)" onkeydown="www_jb51_net(this)" name="account" id="account">