选择下拉框条件关联

//通过数据字典读取select的option
<td>城市</td>
<td><ef:sysDicItemList name="areaId" dictionaryCode="AREA_CODE" value="${param.areaId}" onchange="changeSelectAll()"/></td>

<td nowrap="nowrap" >厂家</td>
<td><ef:sysDicItemList name="manufactuer" id="manufactuer" dictionaryCode="EMS_VENDOR" value="${param.manufactuer}" onchange="changeSelectAll()"/></td>

<td nowrap="nowrap" >名称</td>
<td><input id="sourceId" style="display: none;"/>
<input id="sourceName" type="text" value="" onclick="showEmsList();" >
<div id="emsDiv" style="display: none; position: absolute; width: 250px; height: 200px; z-index: 9999; overflow: auto; background: #fff; border: 1px solid;">
<div class="checkAll" style="height: 20px; cursor: pointer; border: 1px solid #eef6fb;">&nbsp; 
<input type="checkbox" class="chkBorder" value="ALL"
onclick="choseAllEms();" /><a><spring:messagecode="aniam.pub.checkall" /></a></div>
<c:forEach items="${ef:getAlarmSourceList('','')}" var="v"
varStatus="n">
<div class="${v.areaId} vendor${v.manufactuer}" style="height: 20px; cursor: pointer; border: 1px solid #eef6fb;">&nbsp; 
<input id="checkId" name="checkId" type='checkbox'
value="${v.sourceId}" onclick="checkEms();"
title="${v.sourceName}"><a>${v.sourceName}</a>
</div>
</c:forEach>
</div> 
</input></td>

function changeSelectAll(){        
        if(jQuery("#areaId").val() == "" && jQuery("#manufactuer").val() == ""){
            jQuery("#emsDiv div").show();
        }else if(jQuery("#areaId").val() == "" && jQuery("#manufactuer").val() != ""){
            jQuery("#emsDiv div").hide();
            jQuery("."+jQuery("#checkAll").val()).show();
            jQuery(".vendor"+jQuery("#manufactuer").val()).show();
        }else if(jQuery("#areaId").val() != ""&& jQuery("#manufactuer").val() == ""){
            jQuery("#emsDiv div").hide();
            jQuery("."+jQuery("#checkAll").val()).show();
            jQuery("."+jQuery("#areaId").val()).show();
        }else{
            jQuery("#emsDiv div").hide();
            jQuery("."+jQuery("#checkAll").val()).show();
            jQuery("."+jQuery("#areaId").val() + ".vendor"+jQuery("#manufactuer").val()).show();
            
        }