Check Various Credit Card Validation In JS

This is code for check that enter card number with respect to card is valid or u enter wrong card number. Because every card or bank have different digit in his card and it's number.







function checkCreditCard (cardnumber, cardname) {
    
  // Array to hold the permitted card characteristics
  var cards = new Array();


// Define the cards we support. You may add addtional card types.
    
  //  Name:      As in the selection box of the form - must be same as user's
  //  Length:    List of possible valid lengths of the card number for the card
  //  prefixes:  List of possible prefixes for the card
  //  checkdigit Boolean to say whether there is a check digit
  
  cards [0] = {name: "Visa",
  length: "13,16",
  prefixes: "4",
  checkdigit: true};
  cards [1] = {name: "MasterCard",
  length: "16",
  prefixes: "51,52,53,54,55",
  checkdigit: true};
  cards [2] = {name: "DinersClub",
  length: "14,16",
  prefixes: "305, 36, 38, 54,55",
  checkdigit: true};
  cards [3] = {name: "CarteBlanche",
  length: "14",
  prefixes: "300,301,302,303,304,305",
  checkdigit: true};
  cards [4] = {name: "AmEx",
  length: "15",
  prefixes: "34,37",
  checkdigit: true};
  cards [5] = {name: "Discover",
  length: "16",
  prefixes: "6011,622,64,65",
  checkdigit: true};
  cards [6] = {name: "JCB",
  length: "16",
  prefixes: "35",
  checkdigit: true};
  cards [7] = {name: "enRoute",
  length: "15",
  prefixes: "2014,2149",
  checkdigit: true};
  cards [8] = {name: "Solo",
  length: "16,18,19",
  prefixes: "6334, 6767",
  checkdigit: true};
  cards [9] = {name: "Switch",
  length: "16,18,19",
  prefixes: "4903,4905,4911,4936,564182,633110,6333,6759",
  checkdigit: true};
  cards [10] = {name: "Maestro",
  length: "12,13,14,15,16,18,19",
  prefixes: "5018,5020,5038,6304,6759,6761",
  checkdigit: true};
  cards [11] = {name: "VisaElectron",
  length: "16",
  prefixes: "417500,4917,4913,4508,4844",
  checkdigit: true};
  cards [12] = {name: "LaserCard",
  length: "16,17,18,19",
  prefixes: "6304,6706,6771,6709",
  checkdigit: true};
  
  // Establish card type
  var cardType = -1;
  for (var i=0; i<cards.length; i++) {


// See if it is this card (ignoring the case of the string)
  if (cardname.toLowerCase () == cards[i].name.toLowerCase()) {
  cardType = i;
  break;
  }
  }
  
  // If card type not found, report an error
  if (cardType == -1) {
  ccErrorNo = 0;
  return false;
  }
  
  // Ensure that the user has provided a credit card number
  if (cardnumber.length == 0)  {
  ccErrorNo = 1;
  return false;
  }
  
  // Now remove any spaces from the credit card number
  cardnumber = cardnumber.replace (/\s/g, "");
  
  // Check that the number is numeric
  var cardNo = cardnumber
  var cardexp = /^[0-9]{13,19}$/;
  if (!cardexp.exec(cardNo))  {
  ccErrorNo = 2;
  return false;
  }
  
  // Now check the modulus 10 check digit - if required
  if (cards[cardType].checkdigit) {
  var checksum = 0;                                  // running checksum total
  var mychar = "";                                   // next char to process
  var j = 1;                                         // takes value of 1 or 2
  
  // Process each digit one by one starting at the right
  var calc;
  for (i = cardNo.length - 1; i >= 0; i--) {






  // Extract the next digit and multiply by 1 or 2 on alternative digits.
  calc = Number(cardNo.charAt(i)) * j;
  
  // If the result is in two digits add 1 to the checksum total
  if (calc > 9) {
  checksum = checksum + 1;
  calc = calc - 10;
  }
  
  // Add the units element to the checksum total
  checksum = checksum + calc;
  
  // Switch the value of j
  if (j ==1) {j = 2} else {j = 1};
  }
  
  // All done - if checksum is divisible by 10, it is a valid modulus 10.
  // If not, report an error.
  if (checksum % 10 != 0)  {
  ccErrorNo = 3;
  return false;
  }
  }


// The following are the card-specific checks we undertake.
  var LengthValid = false;
  var PrefixValid = false;
  var undefined;


// We use these for holding the valid lengths and prefixes of a card type
  var prefix = new Array ();
  var lengths = new Array ();
  
  // Load an array with the valid prefixes for this card
  prefix = cards[cardType].prefixes.split(",");
  
  // Now see if any of them match what we have in the card number
  for (i=0; i<prefix.length; i++) {
  var exp = new RegExp ("^" + prefix[i]);
  if (exp.test (cardNo)) PrefixValid = true;
  }
  
  // If it isn't a valid prefix there's no point at looking at the length
  if (!PrefixValid) {
  ccErrorNo = 3;
  return false;
  }
  
  // See if the length is valid for this card
  lengths = cards[cardType].length.split(",");
  for (j=0; j<lengths.length; j++) {
  if (cardNo.length == lengths[j]) LengthValid = true;
  }
  
  // See if all is OK by seeing if the length was valid. We only check the
  // length if all else was hunky dory.
  if (!LengthValid) {
  ccErrorNo = 4;
  return false;
  };
  
  // The credit card is in the required format.
  return true;
  }
  function validateCard (errorField) {
  cardText = document.getElementById('txtCardNumber');
  myCardNo = document.getElementById('txtCardNumber').value;
  myCardType = document.getElementById('cardType').value;
  if (checkCreditCard (myCardNo,myCardType))
  {
  errorField.style.visibility='hidden';
  errorField.innerHTML="";
  cardText.style.border='#339900 solid 1px';
  return "";
  }
  else
  {//alert (ccErrors[ccErrorNo])
  errorField.innerHTML="Credit card number is invalid";
  errorField.style.visibility='visible';
  errorField.style.border='#FF3333 solid 1px';
  errorField.style.background='#FBE3E4';
  errorField.style.color='#8a1f11';
  errorField.style.fontSize='10px';
  cardText.style.border='#FF3333 solid 1px';
  return false;
  }
  }