credit card validator in Ruby

credit.rb

cardnumber = 4012888888881881

def validlen?(arr)
  #checks for card length of 13, 15, or 16
  arr.length == 13  || arr.length == 15 || arr.length == 16
end

def arr_split(card_array)
  #recieves array and select even or odd values and creates seperate arrays  
  select_odd_values = card_array.values_at(* card_array.each_index.select {|i| i.odd?})
  select_even_values = card_array.values_at(* card_array.each_index.select {|i| i.even?})
  if card_array.length.odd?
    #maps the first array and muliftiply by 2
    arr1 = select_odd_values.map{|e| e * 2}
    arr2 = select_even_values
  else
    #maps the first array and multiply by 2
    arr1 = select_even_values.map{|e| e * 2}
    arr2 = select_odd_values
  end
  #returns an object of both arrays
  arr = {"arr1" => arr1, "arr2" => arr2 }
end

def sum_arr_digits(array)
  #convert to string and regex match for single digit and map to array
  #reduce all digits
  array.to_s.scan(/\d/).map(&:to_i).reduce(:+)
end

def validator(cardnumber)
  #convert int to char and create array and convert char back to int
  card_array = cardnumber.to_s.split(//).map{|char| char.to_i }
  #pass array of int into length validator
  if validlen?(card_array)
    #collect array of both array in an object
    split_arr =  arr_split(card_array)
    #Add all digits of both arrays together
    checksum = sum_arr_digits(split_arr["arr1"]) + split_arr["arr2"].reduce(:+)
    #Check if the checksum ends with a 0
    if checksum % 10 == 0 

        type_validator_arr = card_array.slice(0,2)
        #Int of the first numbers in the array
        type_validator_int = type_validator_arr.join.to_i
        if type_validator_arr[0] == 4
        return "VISA"
        elsif type_validator_int == 34 || type_validator_int == 37
        return "AMERICAN EXPRESS"
        elsif typeValidatorInt == 22 || typeValidatorInt == 51 || typeValidatorInt == 52 || typeValidatorInt == 53 || typeValidatorInt == 54
            return "MASTERCARD"
        elsif typeValidatorInt == 35 
            return "JCB"
        elsif typeValidatorInt == 60 
            return "DISCOVER"
        elsif typeValidatorInt == 30 
            return "DINERS CLUB"
        end

    else
        return "INVALID"
    end
else
    return "INVALID"
    end
end

puts validator(cardnumber)

Hey! Great article in Medium! I enjoyed reading.

For line 50, you can write it a bit more concisely with the .include? method.
elsif [22, 51, 52, 53, 54].include? typeValidatorInt