Credit Card Checker

// 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];

const mysteryCards = [
  [4, 5, 3, 2, 7, 7, 8, 7, 7, 1, 0, 9, 1, 7, 9, 5],
  [5, 7, 9, 5, 5, 9, 3, 3, 9, 2, 1, 3, 4, 6, 4, 3],
  [3, 7, 5, 7, 9, 6, 0, 8, 4, 4, 5, 9, 9, 1, 4],
  [6, 0, 1, 1, 1, 2, 7, 9, 6, 1, 7, 7, 7, 9, 3, 5],
  [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];


// Add your functions below:
function validateCred(arr){
  let length = arr.length;   //15
  let numbersArr = [];
  for (let i = length - 1; i >= 0 ; i-=2){
    numbersArr.push(arr[i])
  }
  for(let j = length - 2; j >= 0; j-=2){
    let twicedNum = arr[j] * 2;
    if(twicedNum > 9){
      twicedNum -= 9;
    }
    numbersArr.push(twicedNum);
  }
  let sum = numbersArr.reduce((a, b) => a + b);
  return sum % 10 == 0;
} 

function findInvalidCards(misteryCards){
  //let validCards = [];
  let invalidCards = [];
  for(let i = 0; i < misteryCards.length; i++){
    if(!validateCred(misteryCards[i])){
      invalidCards.push(misteryCards[i]);      
    }/* else{
      validCards.push(misteryCards[i])
    } */
  }
  return invalidCards;
}

function idInvalidCardCompanies(invalidCards){
  let invalidCompanies = [];
  let companies = {
    3: "Amex (American Express)",
    4: "Visa",
    5: "Mastercard",
    6: "Discover" 
  }
  for(let i = 0; i < invalidCards.length; i++){
    let firstDigit = invalidCards[i][0];
    if(companies.hasOwnProperty(firstDigit)){
      if(!invalidCompanies.includes(companies[firstDigit])){
        invalidCompanies.push(companies[invalidCards[i][0]]);
      }
    }else{
      console.log("Company not found");
    }
  }
  return invalidCompanies;
}

// TEST

console.log("Invalid cards: ");
let invalidCards = findInvalidCards(mysteryCards);
console.log(invalidCards);
// Output 
// Invalid cards: 
// [ [ 4, 5, 3, 2, 7, 7, 8, 7, 7, 1, 0, 9, 1, 7, 9, 5 ],
//   [ 5, 7, 9, 5, 5, 9, 3, 3, 9, 2, 1, 3, 4, 6, 4, 3 ],
//   [ 3, 7, 5, 7, 9, 6, 0, 8, 4, 4, 5, 9, 9, 1, 4 ],
//   [ 6, 0, 1, 1, 1, 2, 7, 9, 6, 1, 7, 7, 7, 9, 3, 5 ],
//   [ 5, 3, 8, 2, 0, 1, 9, 7, 7, 2, 8, 8, 3, 8, 5, 4 ] ]

console.log(`Campanies who issued invalid cards: ${idInvalidCardCompanies(invalidCards)}`);
// Output
// "Campanies who issued invalid cards: Visa,Mastercard,Amex (American Express),Discover"