<select class="test" id="projectno" name="projectno">       
          <option value="">&nbsp请输入您的所在小区</option>
            <volist name="cell" id="vo">
                <option value="{$vo['id']}">{$vo['name']}</option>
            </volist>
 </select>

想要获取循环的值,把默认值的value设置为空就可以:

 var cell = $.trim($("#projectno").val());