var is_ie = (navigator.userAgent.indexOf('MSIE') >= 0) ? 1 : 0; 
var is_ie5 = (navigator.appVersion.indexOf("MSIE 5.5")!=-1) ? 1 : 0; 
var is_opera = ((navigator.userAgent.indexOf("Opera6")!=-1)||(navigator.userAgent.indexOf("Opera/6")!=-1)) ? 1 : 0; 
//netscape, safari, mozilla behave the same??? 
var is_netscape = (navigator.userAgent.indexOf('Netscape') >= 0) ? 1 : 0; 


function GetXmlHttpObject(handler) { 
    var objXmlHttp = null;    //Holds the local xmlHTTP object instance 

    //Depending on the browser, try to create the xmlHttp object 
    if (is_ie){ 
        //The object to create depends on version of IE 
        //If it isn't ie5, then default to the Msxml2.XMLHTTP object 
        var strObjName = (is_ie5) ? 'Microsoft.XMLHTTP' : 'Msxml2.XMLHTTP'; 
         
        //Attempt to create the object 
        try{ 
            objXmlHttp = new ActiveXObject(strObjName); 
            objXmlHttp.onreadystatechange = handler; 
        } 
        catch(e){ 
        //Object creation errored 
            alert('IE detected, but object could not be created. Verify that active scripting and activeX controls are enabled'); 
            return; 
        } 
    } 
    else if (is_opera){ 
        //Opera has some issues with xmlHttp object functionality 
        alert('Opera detected. The page may not behave as expected.'); 
        return; 
    } 
    else{ 
        // Mozilla | Netscape | Safari 
        objXmlHttp = new XMLHttpRequest(); 
        objXmlHttp.onload = handler; 
        objXmlHttp.onerror = handler; 
    } 
     
    //Return the instantiated object 
    return objXmlHttp; 
} 


// XMLHttp send GET request 
function xmlHttp_Get(xmlhttp, url) { 
    xmlhttp.open('GET', url, true); 
    xmlhttp.send(null); 
}