[Solution] Challenge Project by CodeAcademy on Back-End Engineer Career Path

credit-card-checker.js

// 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:

function validateCred(array) {
    let sum = 0;
    for (let i = array.length - 2; i >= 0; i--) {
        let digit = array[i];
        if (i % 2 === 0) digit *= 2;
        if (digit > 9) {
            digit -= 9;
        }
        sum += digit;
    }
    sum += array[array.length - 1];
    return sum % 10 === 0;
}

function findInvalidCards(array) {
    return array.filter((element) => !(validateCred(element)));
}

function idInvalidCardCompanies(array) {
    const invalidCards = findInvalidCards(array);
    let [amex, visa, mastercard, discover, nocompany] = Array(5).fill(true);
    let companies = [];
    for (let i = 0; i < array.length; i++) {
        if (!amex && !visa && !mastercard && !discover && !nocompany ) break;
        let card = array[i];
        if (card.length === 15 && card[0] === 3 && amex) {
            companies.push('Amex (American Express)');
            amex = false;
        } else if (card.length === 16 && card[0] === 4 && visa) {
            companies.push('Mastercard');
            visa = false;
        } else if (card.length === 16 && card[0] === 5 && mastercard) {
            companies.push('Visa');
            mastercard = false;
        } else if (card.length === 16 && card[0] === 6 && discover) {
            companies.push('Discover');
            discover = false;
        } else {
            companies.push('Company not found');
            nocompany = false;
        }
    }
    return companies;
}

function stringToArray(string) {
    let returnArray = [];
    for(let i = 0; i < string.length; i++) {
        returnArray.push(Number(string[i]));
    }
    return returnArray;
}

// console.log(validateCred(invalid1));
// console.log(findInvalidCards(batch));
console.log(idInvalidCardCompanies(batch));