function ajax(callback){
    var http;
    var callback;
    this.send=function (url,db,func,method){
        callback=func;
        method=method?method:"POST";
        http=null;
        if(window.ActiveXObject){
            http = new ActiveXObject("Microsoft.XMLHTTP");
        }else if(window.XMLHttpRequest){
            http = new XMLHttpRequest();
        }
        http.onreadystatechange=this.f;
        if(method=="GET"){
            url+="?"+db;
            db=null;
        }
        http.open(method,url,true);
		http.setRequestHeader("If-Modified-Since","0");
        http.setRequestHeader("Content-Type","application/x-www-form-urlencoded");
        http.send(db);
    }
    this.f=function (){
        if(http.readyState == 4){
            if(http.status == 200){
                var reback = http.responseText;
                callback(reback);
                http=null;
            }
        }
    }
}
/*
function callback(result){
  document.getElementById('site').innerHTML = result;
}
var ajax = new ajax();
ajax.send("/api/search_site.php","url="+encodeURIComponent('v365v.net'),callback,"GET");
<?php
set_time_limit(10);
header('Cache-Control: no-cache, must-revalidate');
header('Pragma: no-cache');
header('Content-Type: text/plain; charset=gb2312');
echo $str;
?>
*/