cardGenerator.js

createFakeCard(prefix, length) {
    var ccnumber = prefix;

    // generate digits

    while (ccnumber.length < length - 1) {
      ccnumber += Math.floor(Math.random() * 10);
    }

    // reverse number and convert to int

    var reversedCCnumberString = ccnumber
      .split("")
      .reverse()
      .join(""); //strrev(ccnumber);

    var reversedCCnumber = reversedCCnumberString.split("").map(function(x) {
      return parseInt(x);
    });

    var sum = 0;
    var pos = 0;

    while (pos < length - 1) {
      var odd = reversedCCnumber[pos] * 2;
      if (odd > 9) {
        odd -= 9;
      }

      sum += odd;

      if (pos != length - 2) {
        sum += reversedCCnumber[pos + 1];
      }
      pos += 2;
    }

    // calculate check digit

    var checkdigit = ((Math.floor(sum / 10) + 1) * 10 - sum) % 10;
    ccnumber += checkdigit;

    return ccnumber.toString();
  }