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];

// 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) {
  const lastRemoved = [...arr].slice(0, -1);
  const reversed = lastRemoved.reverse();
  for (i = 0; i < reversed.length; i++) {
    if (i % 2 === 0) {
      reversed[i] = reversed[i] * 2;
    };
    if (reversed[i] > 9) {
      reversed[i] = reversed[i] - 9;
    };
  };
  const digitSum = reversed.reduce((previousValue, currentValue) => previousValue + currentValue, arr[arr.length-1]);
  if (digitSum % 10 === 0) {
    return true;
  } else {
    return false;
  }
}

let invalidCards = [];

function findInvalidCards(arr1) {
  for (j = 0; j < arr1.length; j++) {
     if (validateCred(arr1[j]) === false) {
       invalidCards.push(arr1[j]);
     };
    };
    return invalidCards;
  };

let invalidCardCompanies = [];

function idInvalidCardCompanies(arr2) {
  for (k = 0; k < arr2.length; k++) {
    if (arr2[k][0] === 3 && !invalidCardCompanies.includes('Amex')) {
      invalidCardCompanies.push('Amex');
    };
    if (arr2[k][0] === 4 && !invalidCardCompanies.includes('Visa')) {
      invalidCardCompanies.push('Visa');
    };
    if (arr2[k][0] === 5 && !invalidCardCompanies.includes('Mastercard')) {
      invalidCardCompanies.push('Mastercard');
    };
    if (arr2[k][0] === 6 && !invalidCardCompanies.includes('Discover')) {
      invalidCardCompanies.push('Discover');
    };
  };
  return invalidCardCompanies;
}  

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