Credit Card Checker Challenge Project

gistfile1.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(cardArray) {
  // Check if the input is an array of numbers
  if (!Array.isArray(cardArray) || cardArray.length === 0) {
    return false;
  }

  // Reverse the array to start from the rightmost digit
  const reversedArray = cardArray.slice().reverse();

  let sum = 0;
  for (let i = 0; i < reversedArray.length; i++) {
    let digit = reversedArray[i];
    
    // Double every second digit
    if (i % 2 === 1) {
      digit *= 2;
      if (digit > 9) {
        digit -= 9;
      }
    }

    sum += digit;
  }

  // Check if the sum is a multiple of 10
  return sum % 10 === 0;
}

// Example usage:
// const isValid = validateCred(invalid1);
// console.log(isValid); 

function findInvalidCards(nestedArray) {
  const invalidCards = [];
  for (let i=0; i<nestedArray.length; i++) {
    let isValid = validateCred(nestedArray[i]);
    if (!isValid) {
      invalidCards.push(nestedArray[i])
    }
  }
  return invalidCards
}

// const invalidCards = findInvalidCards(batch);
// console.log(invalidCards)

function idInvalidCardCompanies(batch) {
  const companyCodes = {
    3: "Amex (American Express)",
    4: "Visa",
    5: "Mastercard",
    6: "Discover"
  };
  const companies = [];
  invalidCardNumbers = findInvalidCards(batch);

  for (let i = 0; i < invalidCardNumbers.length; i++) {
    const firstDigit = invalidCardNumbers[i][0];
    if (companyCodes[firstDigit] && !companies.includes(companyCodes[firstDigit])) {
      companies.push(companyCodes[firstDigit]);
    } else {
      console.log("Company not found");
    }
  }

  return companies;
}

// Example usage:
const invalidCards = [
  [3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7, 8], // Invalid Amex
  [4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9], // Invalid Visa
  [5, 4, 3, 2, 1, 0, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0], // Invalid Mastercard
  [6, 5, 4, 3, 2, 1, 0, 9, 8, 7, 6, 5, 4, 3, 2, 1]  // Invalid Discover
];

const invalidCompanies = idInvalidCardCompanies(invalidCards);
console.log(invalidCompanies); 

const invalidCompanies2 = idInvalidCardCompanies(batch);
console.log(invalidCompanies2);