# Challenge Project: Credit Card Checker - STEP 3

Hy everyone,

I’ve finished step 3 just now.

However, even though my code works perfectly it keeps printing in the end, the “undefined” word.

I cannot find the solution.

Need help!

Thanks.

// 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 = arr => { for (let k = 0; k <= arr.length - 1; k++) { var total1 = 0; var total2 = 0; let arr = batch[k]; for (let i = arr.length - 2; i >= 0 ; i = i - 2) { if (arr[i] * 2 > 9) { arr[i] = arr[i] * 2 - 9; } else { arr[i] = arr[i] * 2; } total1 += arr[i]; } for(let j = arr.length - 1; j >= 0; j = j - 2) { if (arr[j] < 10) { arr[j]; } total2 += arr[j]; } sum = total1 + total2; if (sum % 10 === 0) { console.log('Valid!'); } else { console.log('Invalid.') } //console.log(total1); //console.log(total2); //console.log(sum); } } console.log(validateCred(batch));

Because your function isn’t returning anything. Remove console.log and just call

``````validateCred(batch);
``````
2 Likes

Thank you!

I think I got it.

The function was already printing “valid!” or “Invalid.”

so when I call console.log at the and it doesn’t return anything.