兼容性问题


var http_request = false;
function send_request(method,url,content,responseType,callback){ http_request=false;
if(window.XMLHttpRequest){//Mozilla浏览器
http_request=new XMLHttpRequest();
if(http_request.overrideMimeType){
http_request.overrideMimeType("text/xml");
}
}
else{
try{
http_request=new ActiveXObject("Msxml2.XMLHTTP");
}catch(e){
try{
http_request=new ActiveXObject("Microsoft.XMLHTTP"); }catch(e){}
}
}
if(!http_request){
window.alert("不能创建XMLHttpRequest对象实例。");
return false;
}
if(responseType.toLowerCase()=="text"){
http_request.onreadystatechange=callback;
}else{

window.alert("响应类别参数错误。");
return false;
}
if(method.toLowerCase()=="get"){
http_request.open(method,url,true);

}
else if(method.toLowerCase()=="post"){
http_request.open(method,url,true);
http_request.setRequestHeader("Content-Type","application/x-www-form-urlencoded");
}else{
window.alert("http请求类别参数错误。");
return false;
}
http_request.send(content);
}//处理返回文本格式信息的函数
function processTextResponse(){
if(http_request.readyState==4){
if(http_request.status==200){
alert("Text文档响应");
}else{
alert("您所请求的页面有异常。");
}
}
}
function processXMLResponse(){
if(http_request.readyState==4){
if(http_request.status==200){
alert("XML文档响应");
}else{
alert("您所请求的页面有异常。");
}
}
}
                    function changFirst(va)
{
                        window.alert(va);
if(va!='0')
{
            var Second = document.getElementById("Second");
                Second.disabled=true;
            var Third = document.getElementById("Third");
                Third.disabled=true;
                
    var f=document.getElementById("Third");
    f.options.length=1;
    var url="Handler.ashx?type=First&id="+va;
    send_request("GET",url,null,"text",populateClass3);
}
}
function populateClass3(){
    var f=document.getElementById("Second");
    var strSecond="";
    if(http_request.readyState==4){
        if(http_request.status==200){
        var list=http_request.responseText;
        
        if(list.length>1){
           var Second = document.getElementById("Second");
                           Second.disabled=false;
                           }
        var classList=list.split("|");
        f.options.length=1;
        for(var i=0;i<classList.length;i++){
        var tmp=classList[i].split(",");
         window.alert(f);
        f.add(new Option(tmp[1],tmp[0]));  
        
        //f+ = '<option value='+tmp[1]+'>'+tmp[0]+'</option>'
        strSecond+= '<option value='+tmp[1]+'>'+tmp[0]+'</option>';
        
     
        }
        }else{
        alert("您所请求的页面有异常。");
        }
    }
}
function changSecond(va)
{
 
    if(va!='0')
    {
    var Third = document.getElementById("Third");
    
                Third.disabled=true;
    
        var url="Handler.ashx?type=Second&id="+va;
    send_request("GET",url,null,"text",populateClass4);
    
    }
}
function populateClass4(){
    var f=document.getElementById("Third");
    if(http_request.readyState==4){
    if(http_request.status==200){
    var list=http_request.responseText;
    if(list.length>1){
        var Third=document.getElementById("Third");
        Third.disabled=false;
    }
    
    var classList=list.split("|");
    f.options.length=1;
    for(var i=0;i<classList.length;i++){
    var tmp=classList[i].split(",");
    f.add(new Option(tmp[1],tmp[0]));
    }
    }else{
    alert("您所请求的页面有异常。");
    }
    }
        }