Generate a valid random credit card number, CVV, issuer and expiration date

Credit Card Generator

/**
 * Generate a valid random credit card number, CVV, issuer and expiration date
 * 
 * Original Copywrite/license:
 *
 * Copyright (c) 2015, Brad Conte (http: *bradconte.com)
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *     * Neither the name of the <organization> nor the
 *       names of its contributors may be used to endorse or promote products
 *       derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.  
 */
function cc_gen() {
    var pos;
    var str = new Array(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0);
    var sum = 0;
    var final_digit = 0;
    var t = 0;
    var len_offset = 0;
    var len = 0;
    var issuerIndex = Math.floor(Math.random() * 3);
    var issuers = ['Mastercard', 'Visa', 'American Express', 'Discover'];
    var issuer = issuers[issuerIndex];
    var CVV = (Math.floor(Math.random() * 9) + 1 + "")
        .concat(Math.floor(Math.random() * 9) + 1 + "")
        .concat(Math.floor(Math.random() * 9) + 1 + "");
    var exp_year = new Date().getFullYear() + Math.floor(Math.random() * 4) + 1;
    var exp_month = Math.floor(Math.random() * 12) + 1

    switch (issuer) {
        case "Visa":
            str[0] = 4;
            pos = 1;
            len = Math.random() > .5 ? 16 : 13;
            break;
        case "Mastercard":
            str[0] = 5;
            t = Math.floor(Math.random() * 5) % 5;
            str[1] = 1 + t; // Between 1 and 5.
            pos = 2;
            len = 16;
            break;
        case "American Express":
            str[0] = 3;
            t = Math.floor(Math.random() * 4) % 4;
            str[1] = 4 + t; // Between 4 and 7.
            pos = 2;
            len = 15;
            CVV = CVV.concat(Math.floor(Math.random() * 9) + 1 + "");
            break;
        case "Discover":
            str[0] = 6;
            str[1] = 0;
            str[2] = 1;
            str[3] = 1;
            pos = 4;
            len = 16;
            break;
    }

    while (pos < len - 1)
        str[pos++] = Math.floor(Math.random() * 10) % 10;

    // Calculate the Luhn checksum of the values thus far.
    len_offset = (len + 1) % 2;
    for (pos = 0; pos < len - 1; pos++) {
        if ((pos + len_offset) % 2) {
            t = str[pos] * 2;
            if (t > 9) {
                t -= 9;
            }
            sum += t;
        } else {
            sum += str[pos];
        }
    }

    // Choose the last digit so that it causes the entire string to pass the checksum.
    final_digit = (10 - (sum % 10)) % 10;
    str[len - 1] = final_digit;
    t = str.join('');
    t = t.substr(0, len);

    return {
        cc: t,
        cvv: CVV,
        issuer: issuer,
        exp_year: exp_year,
        exp_month: exp_month
    }
}