Codecademy export

main.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(arr) {

    let result = 0;
    for (let i = 1; i <= arr.length; i++){
      let newNum = arr[arr.length-i];
      if (i % 2 === 0){
        newNum *= 2;
        if (newNum > 9){
          newNum -= 9;
        }
      }
      result += newNum;
    }
    const remainder = result % 10;
    // console.log(result);
    if (remainder != 0){
      return false;
    }
    return true;
};

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

function idInvalidCardCompanies(invalidCardArrays){
  const output = new Set();
  for (i=0; i< invalidCardArrays.length; i++){
    const firstDigit = invalidCardArrays[i][0];
    switch (firstDigit) {
      case 3:
        output.add('Amex');
        break;
      case 4:
        output.add('Visa');
        break;
      case 5:
        output.add('Mastercard');
        break;
      case 6:
        output.add('Discover');
        break;
      default:
        console.log('Company not found');
    }
  }
  return Array.from(output);
};

console.log(validateCred(invalid3));
const invalidCardNumArr = findInvalidCards(batch);
console.log(idInvalidCardCompanies(invalidCardNumArr));