Validate Credit Card Types

 function ValidateType(cardNumber ,cardType) {
            if (checkCreditCard(cardNumber, cardType.split(' ').join(''))) {
                alert("Credit card has a valid format")
            }
            else { alert(ccErrors[ccErrorNo]) };
        } else {
            alert("Card Type Not Valied");
}

var ccErrorNo = 0;
var ccErrors = new Array()

ccErrors[0] = "Unknown card type";
ccErrors[1] = "No card number provided";
ccErrors[2] = "Credit card number is in invalid format";
ccErrors[3] = "Credit card number is invalid";
ccErrors[4] = "Credit card number has an inappropriate number of digits";

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 as follows.

    //  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: "AMERICANEXPRESS",
        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: "Laser",
        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;

    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;
    }


    if (!LengthValid) {
        ccErrorNo = 4;
        return false;
    };


    return true;
}