Hello,

I am stuck on the credit card checker project please help. The directions and my code is below. Whenever i check valid credit cards it is logging false to the console, but it should be true. Thanks in advance.

Create a function, `validateCred()`

that has a parameter of an array. The purpose of `validateCred()`

is to return `true`

when an array contains digits of a valid credit card number and `false`

when it is invalid. This function should NOT mutate the values of the original array.

To find out if a credit card number is valid or not, use the Luhn algorithm. Generally speaking, an algorithm is a series of steps that solve a problem — the Luhn algorithm is a series of mathematical calculations used to validate certain identification numbers, e.g. credit card numbers. The calculations in the Luhn algorithm can be broken down as the following steps:

- Starting from the farthest digit to the right, AKA the check digit, iterate to the left.
- As you iterate to the left, every other digit is doubled (the check digit is not doubled). If the number is greater than
`9`

after doubling, subtract`9`

from its value. - Sum up all the digits in the credit card number.
- If the sum modulo
`10`

is`0`

(if the sum divided by`10`

has a remainder of`0`

) then the number is valid, otherwise, it’s invalid.

```
//My current code
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 i = arr.length-2; i >= 0; i-= 2) {
arr[i] = (arr[i] * 2) % 9
}
for (let i = 0; i < arr.length; i++) {
let total = 0;
total += arr[i];
if (total % 10 === 0) {
return true;
} else {
return false;
}
}
}
console.log(validateCred(valid1))
```