Html--select

<select id="test" name="test" onchange="doit(this,1);">
     <option value="11">中国</option>
      <option value="12">中国2</option>
</select>
 function doit(obj,stage)
           ...{
//获取  下拉框 的显示内容
           alert(obj.options[obj.options.selectedIndex].text);
//不可以使用  obj.text;

//获取 下拉框的值
           //     var pcatid = obj.options[obj.options.selectedIndex].value;
// 也可以 obj.value;

           }

  <script language=javascript>
  window.onload=init;
  function init()
  ...{
                rescate();

  }
   function rescate()
  ...{
    var res=document.getElementById('cate_1').options[document.getElementById('cate_1').options.selectedIndex].value;
    if(document.getElementById('cate_2'))
    res=document.getElementById('cate_2').options[document.getElementById('cate_2').options.selectedIndex].value;
    if(document.getElementById('cate_3'))
    res=document.getElementById('cate_3').options[document.getElementById('cate_3').options.selectedIndex].value;

    document.getElementById("cate_res").value=res;
    alert(res);
}
var level =0;
var seobj;
var xmlhttp  ;
function doit(obj,stage)
...{
    alert("调用了");
      seobj=obj;
    level=stage;
    var pcatid = obj.options[obj.options.selectedIndex].value;
      if (level>0)...{
              if(level==1)
              ...{
                  document.getElementById("span_2").innerHTML="";
                  document.getElementById("span_3").innerHTML="";
              }
              else if(level ==2 )
              ...{
                  document.getElementById("span_3").innerHTML="";
              }
           if (pcatid > 0 )
           ...{
                  if( window.ActiveXObject)
                  ...{
                    xmlhttp= new ActiveXObject("Microsoft.XMLHTTP")
                  }
                  else if(window.XMLHttpRequest)
                  ...{
                    xmlhttp= new XMLHttpRequest();
                  }
                  var url="/member/ajax/bank.cgi?catid="+pcatid+"&thetime="+new Date().getTime();//设置处理页面和参数
                 alert('ajax');
                  xmlhttp.open("GET",url,false)//设置传参方式
                  xmlhttp.onreadystatechange=whenCompleted;//当状态改变时调用handname
                  xmlhttp.send(null);//执行
         }
      }
}


function whenCompleted()...{
       var pointspan,tname,fun,poption,pval;
 if (xmlhttp.readyState==4)//连接成功
      ...{  //alert(xmlhttp.status)
        if (xmlhttp.status==200)//处理成功
        ...{
         strValue=xmlhttp.responseText;
                            if(level ==1 )//第二级
                          ...{
                          alert("完成函数的第二级");
                              pval = document.getElementById('cate_1').options[document.getElementById('cate_1').options.selectedIndex].value;
//                              if (pval==12)
//                              {poption="<option value='"+pval+"50'>综合</option>";}
                              tname =" name='cate_2' id='cate_2' ";
                              fun   =" onchange=doit(this,2) ";//第二的ajax入口
                              pointspan = "span_2";
                          }
                            else if  (level ==2 )//第三级
                            ...{
                                pval = document.getElementById('cate_2').options[document.getElementById('cate_2').options.selectedIndex].value;
//                                if(pval.indexOf("12")==0)
//                                {
                              poption="<option value='"+pval+"'></option>";
//                            }
                                tname="name='cate_3'";
                                pointspan = "span_3";
                                fun = '';
                            }
                            if( strValue != "")
                            ...{
                              var Strings = "<select " + tname + fun +" >"+ poption + strValue +"</select>";
                              document.getElementById(pointspan).innerHTML = Strings;

                              if(seobj.id=="cate_1" && document.getElementById("cate_2"))
                              ...{
                                  doit(document.getElementById("cate_2"),2);
                              }
                          }
                        }
                    }
               }
</script>