or you can specifically send them as blank ''
onclick="confirm_action(delete, '', '', '')">

Or use the arguments property

function formCheck()
{
  arrayFields = checkForm.arguments;
  arrayLength = (arrayFields.length) - 1;

  for (i=1; i<arrayLength; i++)
  {
    myValue = objForm.elements[arrayFields[i]].value;
    // validate myValue
  }
}