ajax乱码问题

JScript code:

function createRequest(){
if(window.XMLHttpRequest){
httpRequest=new XMLHttpRequest();
}else if(window.ActiveXObject){
try{
httpRequest = new ActiveXObject("Msxml2.XMLHTTP");
}catch(e){
try{
httpRequest = new ActiveXObject("Microsoft.XMLHTTP");
}catch(e){}
}
}
}

function sendRequest(url,nam1,nam2){
createRequest();
id1=nam1
id2=nam2
httpRequest.open("GET",url,true);
httpRequest.setRequestHeader('Content-type', 'application/x-www-form-urlencoded; charset=GB2312');

httpRequest.onreadystatechange=processResponse;
httpRequest.send(null);
}

function processResponse(){
if(httpRequest.readyState == 4){
if(httpRequest.status == 200){
//alert('200');
var result=httpRequest.responseText;
//var result=httpRequest.responseXML//.getElementsByTagName("div");
alert(result);

//var area=document.getElementById(id2);
//area.innerHTML='<textarea rows=7 cols=49>'+result.value+'</textarea>'