//JS
<script type="text/javascript>

//ajax动态给添加原料的【商品名称】下拉框绑定selected属性

                   $("#origin_code").find("option").each(function(index,dom){

                       if($(this).val() == msg.data.origin_code){

                           $(this).attr("selected","selected");

                           return false;

                       }

                   })

</script>

<select name="ajax[origin_code2]" id="origin_code" class="form-control" >

                          <option value="">请选择原料名称</option>

                      <volist name="origin_arr" id="vo">

                          <option value="{$vo.origin_code}" ref="{$vo.origin_unit}" >{$vo.origin_name}</option>

                         </volist>

                      </select>