javascript切换页面

<script language="javascript">
function jumpTo() {
 var d = document.getElementById("jumps").value;
 if (d != "" && d != "intro") {
  contentFrame.location.href = "../contact/dealer_content.jsp?division=" + d;
 }
}
</script>

<select name="jumps" class="select420bl" onChange="jumpTo();">
              <option value="intro">请选择您想要的联系方式</option>
              <option value="">&nbsp;</option>
              <option value="">- - - 汽车 - - -</option>
              <option value="car_services" >博世汽车服务</option>
              <option value="car_parts" >汽车零部件及附件</option>
              <option value="at_oe" >整车汽车技术</option>
              <option value="">&nbsp;</option>
              <option value="">- - - 家居 - - -</option>
              <option value="ha" >家用电器 </option>
              <option value="thermo" >热力技术</option>
              <option value="">&nbsp;</option>
              <option value="">- - - 工业与手工业 - - -</option>
              <option value="security" >安全系统</option>
              <option value="pt" >电动工具</option>
              <option value="packaging" >包装技术</option>
              <option value="automation" >传动及控制技术</option>
       </select>

<table border="0" cellpadding="0" cellspacing="0" width="100%">
        <tr class="blue">
          <td><script language="javascript">
      document.write('<iframe name="contentFrame" id="contentFrame" src="../contact/dealer_content.jsp?division=" width="100%" height="300" scrolling="yes" frameborder="0"></iframe>');
      </script>
          </td>
        </tr>
      </table>