Challenge Project: Credit Card Checker

Description:

The "Credit Card Checker" project is a coding challenge from Codecademy. The purpose of this project is to implement a credit card validation system using the Luhn algorithm. The algorithm checks whether a given credit card number is valid or not.

Project Structure:

• validateCred():

  • Function to validate a credit card number using the Luhn algorithm.
  • Returns true if the credit card number is valid, and false otherwise.
  • Does not mutate the original array.

• findInvalidCards():

  • Function to identify invalid credit card numbers from a nested array of credit card numbers.
  • Uses validateCred() to check the validity of each card number.
  • Returns a nested array of invalid credit card numbers.

• idInvalidCardCompanies():

  • Function to identify the companies that may have issued the faulty credit card numbers.
  • Returns an array of unique company names corresponding to invalid cards.

• fixInvalidCards():

  • Function to fix invalid credit card numbers by applying the Luhn algorithm.
  • Returns an array of fixed credit card numbers.

Usage:

// Example: Validate a credit card number
const isValid = validateCred([4, 5, 5, 6, 7, 3, 7, 5, 8, 6, 8, 9, 9, 8, 5, 5]);
console.log(isValid ? "Card is valid" : "Card is invalid");

// Example: Find invalid cards in a nested array
const invalidCards = findInvalidCards([[...], [...], ...]);
console.log(invalidCards);

// Example: Identify companies with invalid cards
const invalidCompanies = idInvalidCardCompanies(invalidCards);
console.log(invalidCompanies);

// Example: Fix invalid cards
const fixedCards = fixInvalidCards(invalidCards);
console.log(fixedCards);

Luhn Algorithm:

The Luhn algorithm is a mathematical formula used to validate certain identification numbers, such as credit card numbers. The steps of the algorithm include doubling every other digit, subtracting 9 from numbers greater than 9, summing up all the digits, and checking if the sum modulo 10 is 0.

For a visual representation of the Luhn algorithm, refer to the Codecademy diagram here.

Feel free to contribute, report issues, or suggest improvements. Happy coding!