Creditcard number 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];

// 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:
const validateCred = (array) => {
  if (array.length < 16) {
    return "invalid entry";
  }
  let credCheck = 0;
  for (let i = array.length - 1; i >= 0; i--) {
    let tempNum = 0;
    if (i === array.length - 1) {
      credCheck = array[i];
    } else if (i < array.length - 1 && (i + 1) % 2 !== 0) {
      tempNum = array[i] * 2;
      if (tempNum > 9) {
        tempNum -= 9;
      }
    } else {
      tempNum = array[i];
    }
    credCheck += tempNum;
  }
  if (credCheck % 10 == 0) {
    return true;
  }
  return false;
};
const findInvalidCards = (nestArray) => {
  let invalidCards = [];
  for (let i = 0; i < nestArray.length; i++) {
    let result = validateCred(nestArray[i]);
    if (result === false || result === "invalid entry") {
      invalidCards.push(nestArray[i]);
    }
  }
  return invalidCards;
};
let invalid = findInvalidCards(batch);
const idInvalidCardCompanies = (input) => {
  let companies = [];
  let ame;
  let vis;
  let mas;
  let dis;
  for (let i = 0; i < input.length; i++) {
    if (input[i][0] < 3 || input[i][0] > 6) {
      return "Company not found";
    } else {
      switch (input[i][0]) {
        case 3:
          ame = "Amex";
          break;
        case 4:
          vis = "Visa";
          break;
        case 5:
          mas = "Mastercard";
          break;
        case 6:
          dis = "Discover";
      }
    }
  }
  if (ame !== undefined) {
    companies.push(ame);
  }
  if (vis !== undefined) {
    companies.push(vis);
  }
  if (mas !== undefined) {
    companies.push(mas);
  }
  if (dis !== undefined) {
    companies.push(dis);
  }
  return companies;
};
console.log(validateCred(mystery5));
console.log(invalid);

let invalidCompaniesList = idInvalidCardCompanies(invalid);

console.log(invalidCompaniesList);