自分でajaxパッケージの例を実現します。

 //javascript Object: ajax Object
//Created By RexLee
function Ajax(url,data){
    this.url=url;
    this.data=data;
    this.browser=(function(){  
        if(navigator.userAgent.indexOf("MSIE")>0) {  
            return "MSIE";//IE   
        }else{
            return "other";//  
    }})();
};
Ajax.prototype={
    get:function(){
        var result;
        var xmlhttp;
        if(this.browser=='MSIE'){
            try{
                xmlhttp=new ActiveXObject('microsoft.xmlhttp');
                }catch(e){
                    xmlhttp=new ActiveXObject('msxml2.xmlhttp');
                    }
            }else{
                xmlhttp=new XMLHttpRequest();
            };
        xmlhttp.onreadystatechange=function(){
            result = xmlhttp.responseText;//  ，    this.  
        };
        xmlhttp.open('GET',this.url+'?'+this.data,false);//true      ，why?
        xmlhttp.send(null);
        return result;
    },
    post:function(){
        var result;
        var xmlhttp;
        if(this.browser=='MSIE'){
            xmlhttp=new ActiveXObject('microsoft.xmlhttp');
            }else{
                xmlhttp=new XMLHttpRequest();
            };
        xmlhttp.onreadystatechange=function(){
            result = xmlhttp.responseText;//  ，    this.  
        };
        xmlhttp.open('POST',this.url,false);//   false,      responseText
        xmlhttp.setRequestHeader("Content-Type","application/x-www-form-urlencoded");//POST ，    
        xmlhttp.send(this.data);
        return result;
    }
};

//var a=new ajax('opp2.js','');
//alert('by GET\
'+a.get())
//alert('by POST\
'+a.post());
///////////////////////////////

 

window.onload=function(){
document.getElementById("btn").onclick=function(){
    var p=document.getElementById("t").value;
    var a=new Ajax("phpOOP/getPage.php","page="+p);
    document.getElementById("box").innerHTML=a.get();
    };
}