下拉列表选择联动-ajax

//typeScope变化引起missiveType变化
function getMissiveType(){
    var typeScope=$('#typeScope').val();
    $.ajax({
         type:"POST",
         dataType: "json",
         url:"<%=path%>/pages/CommonSession/index.do",
         data:"doaction=searchByMissiveTypeScope&typeScope="+typeScope,
         success:function(data){
               var len=data.length;
               $('#missiveType').attr("length",'0');
               $('<option value=-1>全部</option>').appendTo('#missiveType');
         for(i=0;i<len;i++){
   $('<option value='+data[i].MISSIVE_TYPE_ID+'>'+data[i].NAME+'</option>').appendTo('#missiveType');
}
}
}
);
}
------------------------
          <!--
          <tr>
            <td  width="15%" height="30" bgcolor="ECF4FD" class="tablex">
                <div align="right">公文类别&nbsp;</div></td>
            <td  width="55%" height="30" bgcolor="ECF4FD" class="tableleft">&nbsp;
             <select name="missiveType" id="missiveType" style="width:51%">
                 <option value="" selected="selected">--请选择--</option>
                <c:forEach items="${MissiveTypeBeans}" var="bean">
                  <option value="${bean.MISSIVE_TYPE_ID}" >${bean.NAME}</option>
                </c:forEach>
             </select>
            </td>
          </tr>       
           -->