<script>
    function $(id)
    {
        return document.getElementById(id);
    }
    
    function init()
    {
       
        //初始化之前调用
            var obj=$("area");
            var selectObj=obj;
            var context=$("context");
            var length=context.childNodes.length-1;
            for(var i=length;i>=0;i--)
            {
                if(context.childNodes[i]==selectObj)
                        break;                        
                context.childNodes[i].removeNode(true);
            }        
            obj.length=0;
            var date=new Date();
            ajax("init.action?date="+date,init_callBack);
        
    }
    
        function init_callBack(objXML)
        {
            var selectObj=$("area");
            addInit(selectObj);//固化
            
            var areaArr=objXML.getElementsByTagName("area");
            
            for(var i=0;i<areaArr.length;i++)
            {
                var option=document.createElement("option");
                option.setAttribute("value",areaArr[i].getAttribute("id"));
                option.appendChild(document.createTextNode(areaArr[i].getAttribute("name"))); 
                selectObj.appendChild(option);
                //alert(areaArr[i].getAttribute("name"));
            }
        }
    
    function addInit(obj)
    {
        var opt=document.createElement("option");
        opt.setAttribute("value","");
        opt.appendChild(document.createTextNode("请选择"));
        obj.appendChild(opt)
    }
    
    function ajax(url,method)
        {
              var http_request = new ActiveXObject('Microsoft.XMLHTTP');
             // var date=new Date();
              http_request.open("get",url,"false");
              http_request.onreadystatechange = function()
              {
                  if(4 == http_request.readyState) 
                  {
                     if(200 == http_request.status) 
                     {
                         method(http_request.responseXML);
                     }
                 }
              }
              http_request.setRequestHeader("If-Modifyed-Since","0");
              http_request.send(null);
        }
        
        function addSelect()
        {
            var selectObj=event.srcElement;
            if(selectObj.selectedIndex==0)
            {
                var context=$("context");//得到context组件
                var length=context.childNodes.length-1;
                for(var i=length;i>=0;i--)
                {
                    if(context.childNodes[i]==selectObj)
                     break;
                     context.childNodes[i].removeNode(true)
                }
            }
            else
            {
                var areaId=selectObj.options[selectObj.selectedIndex].getAttribute("value")
                initNext(areaId)
            }
        }
        
        function initNext(areaId)
        {
            var date=new Date()
            ajax("init1.action?index="+areaId+"&date="+date,initNext_callBack);
        }
        
        function initNext_callBack(objXML)
        {
            var _areaArr=objXML.getElementsByTagName("area");
            if(_areaArr.length>0)
            {
                var selectObj_gc=event.srcElement;
                var context_gc=$("context");
                var length=context_gc.childNodes.length-1;
                for(var i=length;i>=0;i--)
                {
                    if(context_gc.childNodes[i]==selectObj_gc)
                        break;
                    context_gc.childNodes[i].removeNode(true);
                }
                var context=$("context");
                var selectObj=document.createElement("select")
                selectObj.onchange=addSelect;
                var optionFirst=document.createElement("option");
                optionFirst.setAttribute("value","");
                optionFirst.appendChild(document.createTextNode("请选择"));
                selectObj.appendChild(optionFirst);
                
                var areaArr=objXML.getElementsByTagName("area");
                for(var i=0;i<areaArr.length;i++)
                {
                    var opt=document.createElement("option");
                    opt.setAttribute("value",areaArr[i].getAttribute("id"));
                    opt.appendChild(document.createTextNode(areaArr[i].getAttribute("name")));
                    selectObj.appendChild(opt);
                }
                context.appendChild(selectObj);
                
            }
            else
            {
                var selectObj_gc=event.srcElement;
                var context_gc=$("context");
                var length=context_gc.childNodes.length-1;
                for(var i=length;i>=0;i--)
                {
                    if(context_gc.childNodes[i]==selectObj_gc)
                    break;
                    context_gc.childNodes[i].removeNode(true);
                }
            }
        }
        

</script>