<!-- Original:  Simon Tneoh (tneohcb@pc.jaring.my) -->
<!-- This script and many more are available free online at -->
<!-- The JavaScript Source!! http://javascript.internet.com -->

<!-- Begin
var Cards = new makeArray(8);
Cards[0] = new CardType("MasterCard", "51,52,53,54,55", "16");
var MasterCard = Cards[0];
Cards[1] = new CardType("Visa card", "4", "13,16");
var VisaCard = Cards[1];
Cards[2] = new CardType("AmExCard", "34,37", "15");
var AmExCard = Cards[2];
Cards[3] = new CardType("DinersClubCard", "30,36,38", "14");
var DinersClubCard = Cards[3];
Cards[4] = new CardType("DiscoverCard", "6011", "16");
var DiscoverCard = Cards[4];
Cards[5] = new CardType("enRouteCard", "2014,2149", "15");
var enRouteCard = Cards[5];
Cards[6] = new CardType("JCBCard", "3088,3096,3112,3158,3337,3528", "16");
var JCBCard = Cards[6];
var LuhnCheckSum = Cards[7] = new CardType();

/*************************************************************************\
CheckCardNumber(form)
function called when users click the "check" button.
\*************************************************************************/
function CheckCardNumber(form) {
	var tmpyear;
	if (form.x_first_name.value.length == 0)
	{
		alert("Please enter your first name.");
		form.x_first_name.focus();
		return false;
	}
	if (form.x_last_name.value.length == 0)
	{
		alert("Please enter your last name.");
		form.x_last_name.focus();
		return false;
	}
	if (form.x_address.value.length == 0)
	{
		alert("Please enter your address.");
		form.x_address.focus();
		return false;
	}
	if (form.x_city.value.length == 0)
	{
		alert("Please enter your city.");
		form.x_city.focus();
		return false;
	}
	if (form.x_state.value.length == 0) {
		alert("Please enter your state.");
		form.x_state.focus();
		return false;
	}
	if (form.x_zip.value.length == 0) {
		alert("Please enter your zip code.");
		form.x_zip.focus();
		return false;
	}
	if (form.x_amount.value.length == 0) {
		alert("Please enter your payment amount.");
		form.x_amount.focus();
		return false;
	}
	if (form.CardNumber.value.length == 0) {
		alert("Please enter a Card Number.");
		form.CardNumber.focus();
		return false;
	}
	if (form.ExpYear.value.length == 0) {
		alert("Please enter the Expiration Year.");
		form.ExpYear.focus();
		return false;
	}
	if (form.ExpYear.value > 96)
		tmpyear = "19" + form.ExpYear.value;
	else if (form.ExpYear.value < 21)
		tmpyear = "20" + form.ExpYear.value;
	else {
		alert("The Expiration Year is not valid.");
		return false;
	}
	tmpmonth = form.ExpMon.options[form.ExpMon.selectedIndex].value;
	// The following line doesn't work in IE3, you need to change it
	// to something like "(new CardType())...".
	// if (!CardType().isExpiryDate(tmpyear, tmpmonth)) {
	if (!(new CardType()).isExpiryDate(tmpyear, tmpmonth)) {
		alert("This card has already expired.");
		return false;
	}
	card = form.CardType.options[form.CardType.selectedIndex].value;
	var retval = eval(card + ".checkCardNumber(\"" + form.CardNumber.value +
	"\", " + tmpyear + ", " + tmpmonth + ");");
	cardname = "";
	if (retval) { 
		isOkay = confirm("You are about to make a payment.  Please verify that the information on the form is correct.  By hitting 'OK' you will be submitting this payment.");
		if (isOkay==false) {  
			return false;
		} else {
			return true;
		}
	}
	else {
		// The cardnumber has the valid luhn checksum, but we want to know which
		// cardtype it belongs to.
		for (var n = 0; n < Cards.size; n++) {
			if (Cards[n].checkCardNumber(form.CardNumber.value, tmpyear, tmpmonth)) {
				cardname = Cards[n].getCardType();
				break;
			}
		}
		if (cardname.length > 0) {
			alert("This looks like a " + cardname + " number, not a " + card + " number.");
			return false;
		}
		else {
			alert("This card number is not valid.");
			return false;
		}
   
   }
}

/*************************************************************************\
Object CardType([String cardtype, String rules, String len, int year, 
                                        int month])
cardtype    : 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 CardType("Visa", "4", "16");
var AmExCard = new CardType("AmEx", "34,37", "15");
\*************************************************************************/
function CardType() {
	var n;
	var argv = CardType.arguments;
	var argc = CardType.arguments.length;

	this.objname = "object CardType";

	var tmpcardtype = (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.setCardType = setCardType;  // setCardType method.
	this.setLen = setLen;  // setLen method.
	this.setRules = setRules;  // setRules method.
	this.setExpiryDate = setExpiryDate;  // setExpiryDate method.

	this.setCardType(tmpcardtype);
	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.getCardType = getCardType;  // getCardType 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 getCardType()
return the cardtype.
\*************************************************************************/
function getCardType() {
	return this.cardtype;
}
/*************************************************************************\
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;
}

/*************************************************************************\
CardType setCardNumber(cardnumber)
return the CardType object.
\*************************************************************************/
function setCardNumber(cardnumber) {
this.cardnumber = cardnumber;
return this;
}

/*************************************************************************\
CardType setCardType(cardtype)
return the CardType object.
\*************************************************************************/
function setCardType(cardtype) {
this.cardtype = cardtype;
return this;
}

/*************************************************************************\
CardType setExpiryDate(year, month)
return the CardType object.
\*************************************************************************/
function setExpiryDate(year, month) {
this.year = year;
this.month = month;
return this;
}

/*************************************************************************\
CardType setLen(len)
return the CardType 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;
}

/*************************************************************************\
CardType setRules()
return the CardType 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;
}

// OLD...
// Credit Card Validation Javascript
// copyright 12th May 2003, by Stephen Chapman, Felgall Pty Ltd

// You have permission to copy and use this javascript provided that
// the content of the script is not changed in any way.

function validateCreditCard(s) {
var v = "0123456789";
var w = "";
for (var i=0; i < s.length; i++) {
x = s.charAt(i);
if (v.indexOf(x,0) != -1)
w += x;
}
var j = w.length / 2;
if (j < 6.5 || j > 8 || j == 7) return false;
var k = Math.floor(j);
var m = Math.ceil(j) - k;
var c = 0;
for (var i=0; i<k; i++) {
a = w.charAt(i*2+m) * 2;
c += a > 9 ? Math.floor(a/10 + a%10) : a;
}
for (var i=0; i<k+m; i++) c += w.charAt(i*2+1-m) * 1;
return (c%10 == 0);
}