[Триви]

<select name="design_tag_type_2">
<option id="tag_1" value="test1">test1</option>
<option id="tag_2" value="test2">test2</option>
<option id="tag_3" value="test3">test3</option>
</select>

<script type='text/javascript'>
(function() {
  var select = document.getElementsByName('design_tag_type_2')[0];
  var options = select.getElementsByTagName('option');
  for (var i=0; i<options.length; i++)  {
    alert(options[i].value);
  }
})();
</script>