javascript信用卡校验代码：Luhn算法校验信用卡真伪

function isValidCreditCard(type, ccnum) {
  if (type == "Visa") {
   // Visa: length 16, prefix 4, dashes optional.
   var re = /^4d{3}-?d{4}-?d{4}-?d{4}$/;
  } else if (type == "MC") {
   // Mastercard: length 16, prefix 51-55, dashes optional.
   var re = /^5[1-5]d{2}-?d{4}-?d{4}-?d{4}$/;
  } else if (type == "Disc") {
   // Discover: length 16, prefix 6011, dashes optional.
   var re = /^6011-?d{4}-?d{4}-?d{4}$/;
  } else if (type == "AmEx") {
   // American Express: length 15, prefix 34 or 37.
   var re = /^3[4,7]d{13}$/;
  } else if (type == "Diners") {
   // Diners: length 14, prefix 30, 36, or 38.
   var re = /^3[0,6,8]d{12}$/;
  }
  if (!re.test(ccnum)) return false;
  // Remove all dashes for the checksum
  //checks to eliminate negative numbers
  ccnum = ccnum.split("-").join("");
  // Checksum ("Mod 10")
  // Add even digits in even length strings
  //or odd digits in odd length strings.
  var checksum = 0;
  for (var i=(2-(ccnum.length % 2)); i<=ccnum.length; i+=2) {
   checksum += parseInt(ccnum.charAt(i-1));
  }
  // Analyze odd digits in even length strings
  //or even digits in odd length strings.
  for (var i=(ccnum.length % 2) + 1; i<ccnum.length; i+=2) {
   var digit = parseInt(ccnum.charAt(i-1)) * 2;
   if (digit < 10) { checksum += digit; }
   else { checksum += (digit-9); }
  }
  if ((checksum % 10) == 0) return true; else return false;
}

<script src="js/WebUIValidation.js" type="text/javascript"></script>
<Script LANGUAGE="JavaScript" type="text/javascript">
<!-- 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("VisaCard", "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.CardNumber.value.length == 0) {
//alert("Please enter the CardNumber");
   // form.CardNumber.focus();
//return false;
//}
if(form.ExpMon.value.length==0)
{
 alert("Please enter the Expiration Month");
 form.ExpMon.focus();
 return false;
}
if(form.ExpMon.value<1|| form.ExpMon.value>12)
{
  alert("The Expiration Month is not valid.");
  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.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)
 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;
}
//  End -->
</Script>