Credit card number validator for Codecademy project.

CC Validator.txt

// All valid credit card numbers
const valid1 = [4, 5, 3, 9, 6, 7, 7, 9, 0, 8, 0, 1, 6, 8, 0, 8];
const valid2 = [5, 5, 3, 5, 7, 6, 6, 7, 6, 8, 7, 5, 1, 4, 3, 9];
const valid3 = [3, 7, 1, 6, 1, 2, 0, 1, 9, 9, 8, 5, 2, 3, 6];
const valid4 = [6, 0, 1, 1, 1, 4, 4, 3, 4, 0, 6, 8, 2, 9, 0, 5];
const valid5 = [4, 5, 3, 9, 4, 0, 4, 9, 6, 7, 8, 6, 9, 6, 6, 6];

// All invalid credit card numbers
const invalid1 = [4, 5, 3, 2, 7, 7, 8, 7, 7, 1, 0, 9, 1, 7, 9, 5];
const invalid2 = [5, 7, 9, 5, 5, 9, 3, 3, 9, 2, 1, 3, 4, 6, 4, 3];
const invalid3 = [3, 7, 5, 7, 9, 6, 0, 8, 4, 4, 5, 9, 9, 1, 4];
const invalid4 = [6, 0, 1, 1, 1, 2, 7, 9, 6, 1, 7, 7, 7, 9, 3, 5];
const invalid5 = [5, 3, 8, 2, 0, 1, 9, 7, 7, 2, 8, 8, 3, 8, 5, 4];

// Can be either valid or invalid
const mystery1 = [3, 4, 4, 8, 0, 1, 9, 6, 8, 3, 0, 5, 4, 1, 4];
const mystery2 = [5, 4, 6, 6, 1, 0, 0, 8, 6, 1, 6, 2, 0, 2, 3, 9];
const mystery3 = [6, 0, 1, 1, 3, 7, 7, 0, 2, 0, 9, 6, 2, 6, 5, 6, 2, 0, 3];
const mystery4 = [4, 9, 2, 9, 8, 7, 7, 1, 6, 9, 2, 1, 7, 0, 9, 3];
const mystery5 = [4, 9, 1, 3, 5, 4, 0, 4, 6, 3, 0, 7, 2, 5, 2, 3];

// An array of all the arrays above
const batch = [
  valid1,
  valid2,
  valid3,
  valid4,
  valid5,
  invalid1,
  invalid2,
  invalid3,
  invalid4,
  invalid5,
  mystery1,
  mystery2,
  mystery3,
  mystery4,
  mystery5,
];

// checks array for valid or invalid credit card numbers
let invalidCards = [];

function validateCred(cardNumArray) {
  let validateNum = cardNumArray.slice(); //creating copy of array

  // iterating through from right to left
  for (let i = validateNum.length - 1; i >= 0; i--) {
    //checking if index is even or odd. If index is even double the value
    if (i % 2 === 0) {
      validateNum[i] *= 2;
    }

    //checking if doubled value is greater than 9, if so, subtract 9
    if (validateNum[i] > 9) {
      validateNum[i] -= 9;
    }
  }

  //adding all values in array together
  const getTotal = (x, y) => x + y;
  let totalToBoolean = validateNum.reduce(getTotal);

  //checking if the total is evenly divisable by 10. If so, set to true(valid card) otherwise false(invalid card)
  if (totalToBoolean % 10 === 0) {
    totalToBoolean = true;
  } else {
    totalToBoolean = false;
  }
  return totalToBoolean;
}

//adds invalid cards to an array
function findInvalidCards(cardNums) {
  for (let i = 0; i < cardNums.length; i++) {
    let checkCards = cardNums[i];

    if (!validateCred(checkCards)) {
      invalidCards.push(checkCards);
    }
  }
  return invalidCards;
}

//loads batch array of all card into function 'findInvalidCards()'
findInvalidCards(batch);

/* checks the array with the invalid card number to see what company they were issued by.
3 = Amex 
4 = Visa
5 = MasterCard
6 = Discover
*/
function invalidCardCompanies(fullNumber) {
  const companyId = [];

  fullNumber.forEach((getFirstNum) => {
    switch (getFirstNum.shift()) {
      case 3:
        companyId.push("Amex");
        break;
      case 4:
        companyId.push("Visa");
        break;
      case 5:
        companyId.push("MasterCard");
        break;
      case 6:
        companyId.push("Discover");
        break;
      default:
        companyId.push("Company not found");
        break;
    }
  });
  return companyId;
}
console.log(invalidCardCompanies(invalidCards));