credit card number checking

credit.js

  CreditCard: {
    TEST_NUMBERS: $w('378282246310005 371449635398431 378734493671000 30569309025904 38520000023237 6011111111111117 6011000990139424 5555555555554444 5105105105105100 4111111111111111 4012888888881881 4222222222222'),

    isValid: function(number){
      if (number.blank()) return false;
      if (Braintree.CreditCard.TEST_NUMBERS.include(number)) return false;

      var total = ($A(number).reverse().inject(0, function(a, n, index) {
        return a + $A((parseInt(n) * [1, 2][index % 2]).toString()).inject(0, function(b, o) {
          return b + parseInt(o);
        });
      }));

      return total % 10 == 0;
    }
  }