Dependant select boxes

// HTML //
<div class="col-md-6">
    <div for='typeId' class="form-group">
      <label for='typeId' class="control-label" >Type</label>
      <select class="form-control" name='typeId' id='typeId' onchange='updateModel()' required >
        <option value=''>Select Type</option>
        <?php
          $qry = "SELECT * FROM trailerType ORDER BY name";
          if(!$res = $dbc->query($qry)) {
            echo "Unavailable";
          } else {
            while($d = $res->fetch_assoc()) {
              echo "<option value='".$d['id']."'";
                if($type_id == $d['id']) {
                  echo " SELECTED='selected'";
                }
              echo ">".$d['name']."</option>";
            }
            $res->free();
          }
        ?>
      </select>
    </div>
  </div>
  <div class="col-md-6">
    <div for='model_id' class="form-group">
      <label for='model_id' class="control-label">Model</label>
      <select class="form-control" name='model_id' id='model_id' required>
        <option value='' typeId=''>Select model</option>
        <?php
          $qry = "SELECT * FROM trailerModel ORDER BY name";
          if(!$res = $dbc->query($qry)) {
            echo "Unavailable";
          } else {
            while($d = $res->fetch_assoc()) {
              echo "<option typeId='".$d['typeId']."' value='".$d['id']."'";
                if($model_id == $d['id']) {
                  echo " SELECTED='selected'";
                }
              echo ">".$d['name']."</option>";
            }
            $res->free();
          }
        ?>
      </select>
    </div>
  </div>
  
  
  //JAVASCRIPT //
  function updateModel() {
			var type = $('#typeId').val();
			$('#model_id option').each(function() { 
				if(($(this).attr('typeid') == type) || ($(this).attr('typeid') == '')) {
					$(this).css('display','block');
				} else {
					$(this).css('display','none');
				}
			});
			if($('#model_id :selected').attr('typeid') != type) {
				$('#model_id').val('');
			}
		}