Codecademy export

main.js

// 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];
const mystery6 = [8, 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,
  mystery6
];

// Add your functions below:

const validateCred = (arr) => {
  let digitSum = 0;
  let revArr = arr.reverse();
  let arrIndexLength = revArr.length - 1;

  for (let x = arrIndexLength; x >= 0; x--) {
    if (x % 2 != 0) {
      if (revArr[x] * 2 > 9) {
        digitSum += revArr[x] * 2 - 9;
      } else {
        digitSum += revArr[x] * 2;
      }
    } else {
      digitSum += revArr[x];
    }
  }

  if (digitSum % 10 === 0) {
    return true;
  } else {
    return false;
  }
};

const findInvalidCards = (nestedArr) => {
  const invalidArr = [];
  const revisedInvalidArr = [];
  for (let x = 0; x < nestedArr.length; x++) {
    if (validateCred(nestedArr[x]) === false) {
      invalidArr.push(nestedArr[x]);
    }
  }
  for (let i = 0; i < invalidArr.length; i++) {
    revisedInvalidArr.push(invalidArr[i].reverse());
  }
  return revisedInvalidArr;
};

const idInvalidCardCompanies = (invalidNestedArr) => {
  let companyArray = [];
  for (let x = 0; x < invalidNestedArr.length; x++) {
    if (invalidNestedArr[x][0] === 3) {
      companyArray.push("Amex");
    } else if (invalidNestedArr[x][0] === 4) {
      companyArray.push("Visa");
    } else if (invalidNestedArr[x][0] === 5) {
      companyArray.push("Mastercard");
    } else if (invalidNestedArr[x][0] === 6) {
      companyArray.push("Discover");
    } else {
      companyArray.push("Unknown Credit Card Vendor");
    }
  }
  companyArray = companyArray.filter(
    (value, index) => companyArray.indexOf(value) === index
  );
  return companyArray;
};

console.log(idInvalidCardCompanies(findInvalidCards(batch)));