Hello,

I’m currently doing the full-stack Engineer Path. I’m at 32%. I have also done the basic Javascript course. For the Credit Card Checker, the function I wrote doesn’t work: I have a an error message when I try it on the array `valid1`

. I would really love and appreciate if anyone could help me, thanks in advance.

Have a great day !

```
// 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 validatedCred = array => {
let newArray = [];
for(let i = array.length - 1; i >=0; i--){
if(i = array.length - 1){
newArray.push(array[i]);
}else{
let toPush = array[i]*2;
if(toPush > 9){
toPush = toPush - 9;
}
newArray.push(toPush);
}
}
const sum = array.reduce(function(a, b){
return a + b;
}, 0);
if(sum % 10 === 0){
return true
}else{
return false
}
}
validatedCred(valid1)
```

Up here is my function.

The message I get :

These are the instructions :

- Remove the last element from the array, (but remember, you don’t want to alter the original array!).
- Reverse the array (now without the last digit).
- Multiply the digits in odd positions (e.g. first digit, third, fifth…etc) by
`2`

. If the resulting number is over`9`

, subtract`9`

from the number. - Add up all the numbers in the array as well as the dropped digit from step 1. If the sum modulo
`10`

is`0`

then the array contains a valid number. Conversely, if the result is any number but`0`

, then the array contains an invalid number.