一个强健 实用的asp+ajax二级联动菜单(有演示和附(5)

        document.getElementById("subclass").innerHTML="<select name='smallclassid'><option value='0' selected>选择二级分类</option></select>";
        return;
    };
    var xmlhttpobj = createxmlhttp();
    if(xmlhttpobj){//如果创建对象xmlhttpobj成功
        xmlhttpobj.open('get',"getsubcategory.asp?bigclassid="+bigclassid+"&number="+Math.random(),true);//get方法 加个随机数。
        xmlhttpobj.send(null);
        xmlhttpobj.onreadystatechange=function(){//客户端监控函数
            if(xmlhttpobj.readystate==4){//服务器处理请求完成
                if(xmlhttpobj.status==200){
                    //alert('ok');
                    var html = xmlhttpobj.responseText;//获得返回值
                    document.getElementById("subclass").innerHTML=html;
                }else{
                    document.getElementById("subclass").innerHTML="对不起，您请求的页面有问题...";
                }
            }else{
                document.getElementById("subclass").innerHTML="加载中，请梢候...";//服务器处理中
            }
        }    
    }
}