# Credit Card Checker Solution- any feedback?

I finally got this to work, I’m sure it could be streamlined some though. Any feedback would be appreciated!
Credit Card Checker Project

// 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) => { let luhnArray = []; let arrayEnd = array.length - 1; for (let i = array.length - 2; i > -1; i--) { array[i] *= 2; if (array[i] > 9) { array[i] -= 9; } luhnArray.unshift(array[i]); i--; if (i >= 0) { luhnArray.unshift(array[i]); } } luhnArray.push(array[arrayEnd]); //sums luhn array let sumArray = luhnArray.reduce((a, b) => a + b); if (sumArray % 10 == 0) { return true; } else { return false; } } // Find invalid cards const findInvalidCards = (nestedArr) => { let invalid = [] for (let i=0; i<nestedArr.length; i++){ if(validateCred(nestedArr[i]) === false){ invalid.push(nestedArr[i]) } } return invalid } // Find Companies const idInvalidCardCompanies = (cards) => { let invalidCards = findInvalidCards(cards) let companies = [] for(let i=0; i<invalidCards.length; i++){ switch(invalidCards[i][0]){ case 3: if(companies.indexOf('Amex (American Express)') === -1){ companies.push('Amex (American Express)')} break; case 4: if(companies.indexOf('Visa') === -1){ companies.push('Visa')} break; case 5: if(companies.indexOf('Mastercard') === -1){ companies.push('Mastercard')} break case 6: if(companies.indexOf('Discover') === -1){ companies.push('Discover')} break default: console.log(`Card \${i} company not found`) } } return companies } console.log(idInvalidCardCompanies(batch))