Codecademy export

main.js

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]

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]

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]

const getSum = (i, array, remainder) => {
    /* Loop through given array, and muliply values of EVEN or ODD indexes by 2 and subtract 9 (if >= 10), to generate sum digits */
    let sum = 0;
    if (i % 2 === remainder) { 
        const n = array[i];
        let multiplied = n * 2;
        if (multiplied >= 10) {
            multiplied -= 9;
            sum += multiplied;
        }
        else {
            sum += multiplied;
        }
    }
    else {
        sum += array[i];
    }
    return sum;
}

const validateCred = array => {
    let check = array[array.length-1];
    let sum = 0;

    for (let i = array.length-2; i >= 0; i--) {
        if (array.length % 2 === 0) {
            sum += getSum(i, array, 0);  // multiply even indexes
        }
        else {
            sum += getSum(i, array, 1);   // multiply odd indexes
        }
    }
    sum += check;
    return sum % 10 === 0;
};

const findInvalidCards = nestedArray => {
    return nestedArray.filter(innerArray => !validateCred(innerArray));
};

const idInvalidCardCompanies = nestedArray => {
    const companies = {3: 'Amex', 4: 'Visa', 5: 'Mastercard', 6: 'Discover'};
    const final = [];
    const temp = [];
    const firstNumbers = nestedArray.map(o => o[0]);
    for (const n of firstNumbers) {
        const number = n.toString();
        for (const [key, value] of Object.entries(companies)) {
            if (number === key) {
                temp.push(value);
            }
        }
    }
    for (const company of temp) {
        if (!final.includes(company)) {
            final.push(company);
        }
    }
    return final;
}

const invalid = findInvalidCards(batch);
console.log(idInvalidCardCompanies(invalid));