var xmlhttp_request; //提取服务器visa信息的http请求对象，一般是Microsoft.XMLHTTP的实例
var m_curVisaName; //用于在查询结果页面上默认选中 在首页中选择的签证类型

/*
获取http请求对象的实例
*/
function GetVisaBySendingRequest(strVisaName)
{
    m_curVisaName = strVisaName;
    
    var strCountryCode = document.getElementById("vs_tocountry").value; //$("#vs_tocountry").val();
    //var vs_visa = eval("vs_visa"); //$("#vs_visa");
    //vs_visa.children().remove();
    if (strCountryCode != ""){
        var strUrl = '/ServiceVisaGetVisaNames.aspx?country=' + escape(strCountryCode); //UrlEncode(strCountryCode);
        xmlhttp_request = GetXmlHttpRequest();
        xmlhttp_request.open("GET", strUrl, true);
        xmlhttp_request.onreadystatechange = CallbackOfHttpResponse;
        xmlhttp_request.send(null);
    }
}

/*
获取http请求对象的实例
*/
function GetXmlHttpRequest()
{
    try{
        if(window.ActiveXObject){ 
            for( var i = 5; i; i-- ){ 
                try{ 
                    if( i == 2 ){ 
                        xmlhttp_request = new ActiveXObject("Microsoft.XMLHTTP"); 
                        return xmlhttp_request;
                    }else{
                        xmlhttp_request = new ActiveXObject( "Msxml2.XMLHTTP." + i + ".0" );
                        xmlhttp_request.setrequestHeader("Content-Type","text/xml");
                        xmlhttp_request.setrequestHeader("Content-Type","UTF-8");  //gb2312
                        return xmlhttp_request;
                    }
                    break;
                }catch(e){
                }
             }
        }else if(window.XMLHttpRequest){
            xmlhttp_request = new XMLHttpRequest();
            if (xmlhttp_request.overrideMimeType){
                xmlhttp_request.overrideMimeType('text/xml'); 
            }
            return xmlhttp_request;
        }
    }catch(e){
        return false;
    }
} 

/*
http请求的Callback函数，将服务器返回的签证类型信息写入SELECT中
*/
function CallbackOfHttpResponse(strVisaName)
{
    if (xmlhttp_request.readyState == 4){
        if (xmlhttp_request.status == 200){
			//已经提取服务器数据的状态
        }else{
            return;
        }
    }else{
        return;
    }

    var response = xmlhttp_request.responseXML;
    
    //alert("response text: " + xmlhttp_request.ResponseText);
    var oRoot=response.getElementsByTagName('visa1');
    if(oRoot.length > 0){
		//先删除SELECT中原来的所有元素
        for(var j=0; j<100; j++){
			try{
				document.getElementById("vs_visa").options.remove(0);
			}catch(ex){
				break;
			}
        }
        
        //将服务器返回的签证类型信息写入SELECT中
        var oOption = document.createElement('OPTION');
        for(var i=0;i<oRoot.length;++i){
            oItem = oRoot.item(i);
            var sName = oItem.getAttribute("name");
            var sValue =  oItem.getAttribute("value");
            var oOption = document.createElement('OPTION');
            oOption.text = sName;
            oOption.value = sValue;
            document.getElementById("vs_visa").options.add(oOption);
            if (m_curVisaName == sValue){
                oOption.selected = true;
            }
        }
    }
}