如何取option自定义属性?

1.SELECT代码:

<select name="zcdq" id="zcdq" class="easyui-validatebox" onchange = "setShq(this)" required="true" >       
  <#if GSDJJGList??>
  <#if (GSDJJGList?size > 0)>            
  <#list GSDJJGList as data2> 
   <option  value="${data2.val?if_exists}" parentcode="${data2.parentcode?if_exists}"
   <#if data.zcdq??><#if data2.val==data.zcdq?string>selected='true'</#if></#if>>
   ${data2.name?if_exists} &nbsp;${data2.parentcode?if_exists}
  </option>
  </#list>
  </#if>
  </#if>             
</select>

2.方法:

function setShq(id){
     alert($(id).find("option:selected").attr("parentcode")); 
}