if (typeof (validate_digits_frontend_captcha_bank) != "function")
{
   function validate_digits_frontend_captcha_bank(event)
   {
      if (event.which != 8 && event.which != 0 && event.which != 13 && (event.which < 48 || event.which > 57))
      {
         event.preventDefault();
      }
   }
}
