<!-- Begin
var Cards = new makeArray(3);
Cards[0] = new CreditCard("MasterCard", "51,52,53,54,55", "16");
var MasterCard = Cards[0];
Cards[1] = new CreditCard("VisaCard", "4", "13,16");
var VisaCard = Cards[1];
Cards[2] = new CreditCard("AmEx", "34,37", "15");
var AmExCard = Cards[2];
Cards[3] = new CreditCard("Discover", "60,61" , "16");
var Discover = Cards[3];
var LuhnCheckSum = Cards[4] = new CreditCard();

/*************************************************************************\
CheckCardNumber(form)
function called when users click the "check" button.
\*************************************************************************/
function CheckCardNumber(form) 
{
	var tmpyear;
	if (form.CreditCard[form.CreditCard.selectedIndex].value==0)
	{
		alert("Select a Credit Card");
		form.CreditCard.focus();
		return false;
	}
	if (form.ExpirationMonth[form.ExpirationMonth.selectedIndex].value==0)
	{
		alert("Select the Expiration Month.");
		form.ExpirationMonth.focus();
		return false;
	}
	if (form.ExpirationYear[form.ExpirationYear.selectedIndex].value == 0) 
	{
		alert("Select the Expiration Year.");
		form.ExpirationYear.focus();
		return false;
	}

	if (form.CardNumber.value.length == 0) 	
	{
		alert("Card Number is required.");
		form.CardNumber.focus();
		return false;
	}

//	if(!isEmpty(form.CardName,"Card Name"))
//		return false;

	tmpyear = 	form.ExpirationYear[form.ExpirationYear.selectedIndex].value;
	tmpmonth = form.ExpirationMonth.options[form.ExpirationMonth.selectedIndex].value;
	if (!(new CreditCard()).isExpiryDate(tmpyear, tmpmonth)) 
	{
		alert("This card has already expired.");
		form.ExpirationMonth.focus();
		return false;
	}
	card = form.CreditCard.options[form.CreditCard.selectedIndex].value;
	var retval = eval(card + ".checkCardNumber(\"" + form.CardNumber.value +
	"\", " + tmpyear + ", " + tmpmonth + ");");
	cardname = "";
	if (!retval)
	// comment this out if used on an order form
	//	alert("This card number appears to be valid.");

//	else
	 {
	// The cardnumber has the valid luhn checksum, but we want to know which
	// CreditCard it belongs to.
	for (var n = 0; n < Cards.size; n++) 
	{
		if (Cards[n].checkCardNumber(form.CardNumber.value, tmpyear, tmpmonth)) 
		{
			cardname = Cards[n].getCreditCard();
			break;
		}
	}
	if (cardname.length > 0) 
	{
		alert("This looks like a " + cardname + " number, not a " + card + " number.");
		form.CardNumber.focus();
		return false;
	}
	else 
	{
		alert("This card number is not valid.");
		form.CardNumber.focus();
		return false;

    }
   }
}
/*************************************************************************\
Object CreditCard([String CreditCard, String rules, String len, int year, 
                                        int month])
CreditCard    : type of card, eg: MasterCard, Visa, etc.
rules       : rules of the cardnumber, eg: "4", "6011", "34,37".
len         : valid length of cardnumber, eg: "16,19", "13,16".
year        : year of expiry date.
month       : month of expiry date.
eg:
var VisaCard = new CreditCard("Visa", "4", "16");
var AmExCard = new CreditCard("AmEx", "34,37", "15");
\*************************************************************************/
function CreditCard() {
var n;
var argv = CreditCard.arguments;
var argc = CreditCard.arguments.length;

this.objname = "object CreditCard";

var tmpCreditCard = (argc > 0) ? argv[0] : "CardObject";
var tmprules = (argc > 1) ? argv[1] : "0,1,2,3,4,5,6,7,8,9";
var tmplen = (argc > 2) ? argv[2] : "13,14,15,16,19";

this.setCardNumber = setCardNumber;  // set CardNumber method.
this.setCreditCard = setCreditCard;  // setCreditCard method.
this.setLen = setLen;  // setLen method.
this.setRules = setRules;  // setRules method.
this.setExpiryDate = setExpiryDate;  // setExpiryDate method.

this.setCreditCard(tmpCreditCard);
this.setLen(tmplen);
this.setRules(tmprules);
if (argc > 4)
this.setExpiryDate(argv[3], argv[4]);

this.checkCardNumber = checkCardNumber;  // checkCardNumber method.
this.getExpiryDate = getExpiryDate;  // getExpiryDate method.
this.getCreditCard = getCreditCard;  // getCreditCard method.
this.isCardNumber = isCardNumber;  // isCardNumber method.
this.isExpiryDate = isExpiryDate;  // isExpiryDate method.
this.luhnCheck = luhnCheck;// luhnCheck method.
return this;
}

/*************************************************************************\
boolean checkCardNumber([String cardnumber, int year, int month])
return true if cardnumber pass the luhncheck and the expiry date is
valid, else return false.
\*************************************************************************/
function checkCardNumber() {
var argv = checkCardNumber.arguments;
var argc = checkCardNumber.arguments.length;
var cardnumber = (argc > 0) ? argv[0] : this.cardnumber;
var year = (argc > 1) ? argv[1] : this.year;
var month = (argc > 2) ? argv[2] : this.month;

this.setCardNumber(cardnumber);
this.setExpiryDate(year, month);

if (!this.isCardNumber())
return false;
if (!this.isExpiryDate())
return false;

return true;
}
/*************************************************************************\
String getCreditCard()
return the CreditCard.
\*************************************************************************/
function getCreditCard() {
return this.CreditCard;
}
/*************************************************************************\
String getExpiryDate()
return the expiry date.
\*************************************************************************/
function getExpiryDate() {
return this.month + "/" + this.year;
}
/*************************************************************************\
boolean isCardNumber([String cardnumber])
return true if cardnumber pass the luhncheck and the rules, else return
false.
\*************************************************************************/
function isCardNumber() {
var argv = isCardNumber.arguments;
var argc = isCardNumber.arguments.length;
var cardnumber = (argc > 0) ? argv[0] : this.cardnumber;
if (!this.luhnCheck())
return false;

for (var n = 0; n < this.len.size; n++)
if (cardnumber.toString().length == this.len[n]) {
for (var m = 0; m < this.rules.size; m++) {
var headdigit = cardnumber.substring(0, this.rules[m].toString().length);
if (headdigit == this.rules[m])
return true;
}
return false;
}
return false;
}

/*************************************************************************\
boolean isExpiryDate([int year, int month])
return true if the date is a valid expiry date,
else return false.
\*************************************************************************/
function isExpiryDate() {
var argv = isExpiryDate.arguments;
var argc = isExpiryDate.arguments.length;

year = argc > 0 ? argv[0] : this.year;
month = argc > 1 ? argv[1] : this.month;

if (!isNum(year+""))
return false;
if (!isNum(month+""))
return false;
today = new Date();
expiry = new Date(year, month);
if (today.getTime() > expiry.getTime())
return false;
else
return true;
}

/*************************************************************************\
boolean isNum(String argvalue)
return true if argvalue contains only numeric characters,
else return false.
\*************************************************************************/
function isNum(argvalue) {
argvalue = argvalue.toString();

if (argvalue.length == 0)
return false;

for (var n = 0; n < argvalue.length; n++)
if (argvalue.substring(n, n+1) < "0" || argvalue.substring(n, n+1) > "9")
return false;

return true;
}

/*************************************************************************\
boolean luhnCheck([String CardNumber])
return true if CardNumber pass the luhn check else return false.
Reference: http://www.ling.nwu.edu/~sburke/pub/luhn_lib.pl
\*************************************************************************/
function luhnCheck() {
var argv = luhnCheck.arguments;
var argc = luhnCheck.arguments.length;

var CardNumber = argc > 0 ? argv[0] : this.cardnumber;

if (! isNum(CardNumber)) {
return false;
  }

var no_digit = CardNumber.length;
var oddoeven = no_digit & 1;
var sum = 0;

for (var count = 0; count < no_digit; count++) {
var digit = parseInt(CardNumber.charAt(count));
if (!((count & 1) ^ oddoeven)) {
digit *= 2;
if (digit > 9)
digit -= 9;
}
sum += digit;
}
if (sum % 10 == 0)
return true;
else
return false;
}

/*************************************************************************\
ArrayObject makeArray(int size)
return the array object in the size specified.
\*************************************************************************/
function makeArray(size) {
this.size = size;
return this;
}

/*************************************************************************\
CreditCard setCardNumber(cardnumber)
return the CreditCard object.
\*************************************************************************/
function setCardNumber(cardnumber) {
this.cardnumber = cardnumber;
return this;
}

/*************************************************************************\
CreditCard setCreditCard(CreditCard)
return the CreditCard object.
\*************************************************************************/
function setCreditCard(CreditCard) {
this.CreditCard = CreditCard;
return this;
}

/*************************************************************************\
CreditCard setExpiryDate(year, month)
return the CreditCard object.
\*************************************************************************/
function setExpiryDate(year, month) {
this.year = year;
this.month = month;
return this;
}

/*************************************************************************\
CreditCard setLen(len)
return the CreditCard object.
\*************************************************************************/
function setLen(len) {
// Create the len array.
if (len.length == 0 || len == null)
len = "13,14,15,16,19";

var tmplen = len;
n = 1;
while (tmplen.indexOf(",") != -1) {
tmplen = tmplen.substring(tmplen.indexOf(",") + 1, tmplen.length);
n++;
}
this.len = new makeArray(n);
n = 0;
while (len.indexOf(",") != -1) {
var tmpstr = len.substring(0, len.indexOf(","));
this.len[n] = tmpstr;
len = len.substring(len.indexOf(",") + 1, len.length);
n++;
}
this.len[n] = len;
return this;
}

/*************************************************************************\
CreditCard setRules()
return the CreditCard object.
\*************************************************************************/
function setRules(rules) {
// Create the rules array.
if (rules.length == 0 || rules == null)
rules = "0,1,2,3,4,5,6,7,8,9";
  
var tmprules = rules;
n = 1;
while (tmprules.indexOf(",") != -1) {
tmprules = tmprules.substring(tmprules.indexOf(",") + 1, tmprules.length);
n++;
}
this.rules = new makeArray(n);
n = 0;
while (rules.indexOf(",") != -1) {
var tmpstr = rules.substring(0, rules.indexOf(","));
this.rules[n] = tmpstr;
rules = rules.substring(rules.indexOf(",") + 1, rules.length);
n++;
}
this.rules[n] = rules;
return this;
}
//  End -->