# Credit Card Checker Challenge Project (JavaScript)

Hi Guys ,
Here is my solution. I was at this for over 12hours accumulated because I couldn’t get valid3 to be true without affecting the rest. Maybe you can suggest something about it.

Looking forward to feedbacks.

``````// 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];

//check all card array passed
const validatesCred = card => {
let currentValue = 0;
for(let i = card.length - 1; i >= 0 ; i--) {
if (i % 2 === 0) {
card[i] *= 2;
if (card[i] > 9) {
card[i] -= 9;
}
}

currentValue += card[i];
}
// test for validity;
if (currentValue % 10 === 0){
return true;
}else{
return false;
}
}

// make invalid cards an empty array
let invalidCards = [];

//find invalid cards
const findInvalidCards = batch => {
for (j = 0; j < batch.length; j++){
if (!validatesCred(batch[j])){
invalidCards.push(batch[j]);
}
}
console.log(invalidCards);
}

// show which companies issued bad cards
const idInvalidCardCompanies = card =>{
let company;
let companies = [];
let id;
for (k = 0; k < card.length; k++) {
id = card[k][0];
switch(id){
case 3:
company = "Amex";
break;
case 4:
company = "Visa";
break;
case 5:
company = "Mastercard";
break;
case 6:
company = "Discover";
break;
default:
}
if (!companies.includes(company)) {
companies.push(company);
}
}
console.log(companies);
}

findInvalidCards(batch);
idInvalidCardCompanies(invalidCards);
``````

Hello, could someone please explain to me what they’re asking me when in comes to creating a function that converts invalid to valid numbers? Do they mean that i need to convert the invalid number to an existing valid number? Or a randomized valid number by figuring out some sort of math equation to achieve that?