js获取select标签的值且兼容IE与firefox

jsp代码：
复制代码代码如下:
<form id="search">
<select id="jobSelect" style="width: 200px;" name="jobSelect">
  <s:if test="jobSelect == null || jobSelect == """>
   <option selected="selected" value="-1">--依职类筛选--</option>
  </s:if>
  <s:else>
   <option value="-1">--依职类筛选--</option>
  </s:else>
  <s:iterator value="jobCat" status="s">
   <s:if test="jobSelect == catKey">
    <option value="<s:property value="catKey" />" selected="selected">
     <s:property value="catCnName" />
    </option>
   </s:if>
   <s:else>
    <option value="<s:property value="catKey" />">
     <s:property value="catCnName" />
    </option>
   </s:else>
  </s:iterator>
</select> <br />
<select id="areaSelect" style="width: 200px;" name="areaSelect">
  <s:if test="areaSelect == null || areaSelect == """>
   <option selected="selected" value="-1">--依地区筛选--</option>
  </s:if>
  <s:else>
   <option value="-1">--依地区筛选--</option>
  </s:else>
  <s:iterator value="workAreaCat" status="s">
   <s:if test="areaSelect == areaCat">
    <option value="<s:property value="areaCat" />" selected="selected">
     <s:property value="catCnName" />
    </option>
   </s:if>
   <s:else>
    <option value="<s:property value="areaCat" />">
     <s:property value="catCnName" />
    </option>
   </s:else>
  </s:iterator>
</select>
<input class="send2" type="button" onclick="validate（）;return false" value="查询" />
<span style="color: red;" mce_style="color: red;" id="requiredParam"></span>
</form>

js代码：
复制代码代码如下:
<mce:script type="text/javascript"><！--
validate = function（）{
  var jobSelect;
  var areaSelect;
  var search = document.getElementById（"search"）;
  for（var i=0;i<search.jobSelect.length;i++）{
   if（search.jobSelect[i].selected）{
    jobSelect = search.jobSelect[i].value;
   }
  }
  for（var i=0;i<search.areaSelect.length;i++）{
   if（search.areaSelect[i].selected）{
    areaSelect = search.areaSelect[i].value;
   }
  }
  if（jobSelect == -1 && areaSelect == -1）{
   document.getElementById（"requiredParam"）.innerHTML = "请设定筛选条件后查询";
   return;
  }
  var param = {
         target : "../Index/JobFrame.action",
         method : "post",
         form   : "search",
         div    : "box"
     }
     var as = new AjaxSender（param）;
     as.send（）
}
// --></mce:script