funcion para validar uina tarjeta de credito luhn

function validateCreditCard(cardNumber){
  let numString = cardNumber.toString();
  let reversedArr = [];
  let auxArr = [];
  let sumArr = [];
  let finalSum = 0;

  for(let i = numString.length-1; i>=0; i--){
    reversedArr.push(numString[i]);
  }
  
  for(let i = 0; i<reversedArr.length; i++){
    if(i%2 == 0){
      let number = Number(reversedArr[i])*2;
      if(number > 9){
        number = (number%10) + 1;
      }
      auxArr.push(number);
    }else{
      auxArr.push(Number(reversedArr[i]));
    }
  }
  
  for(let i = 0; i<auxArr.length; i++){
    finalSum = auxArr[i] + finalSum;
  }
  if(