var isFirefox = false;
var isSafari = false;
var isIE = false;

var browser = window.navigator.userAgent.toLowerCase();



if (browser.indexOf("firefox") > -1)
    isFirefox = true;
else if (browser.indexOf("safari") > -1)  
    isSafari = true;
else
    isIE = true;

function httpRequest(page, operation)
{
    var xmlHttp;
    if (window.XMLHttpRequest)// code for IE7+, Firefox, Chrome, Opera, Safari
        xmlHttp=new XMLHttpRequest();   
           
    else if (window.ActiveXObject)// code for IE6, IE5    
        xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
          
    else  
        alert("Your browser does not support Ajax!");
    
    xmlHttp.onreadystatechange = function()
    {
        if (this.readyState == 4)
        {
            if (typeof(operation) == "function")
                operation(this.responseText);
        }                                                                
    }
    
    var method = "POST";
    if (isFirefox || isSafari)
        method = "GET";
        
        
    xmlHttp.open(method, page, true);
    xmlHttp.send(null);      
}