function createRequestObject() {
    var tmpXmlHttpObject;
    if (window.XMLHttpRequest) { 
        tmpXmlHttpObject = new XMLHttpRequest();
    } else if (window.ActiveXObject) { 
        tmpXmlHttpObject = new ActiveXObject("Msxml2.XMLHTTP");
    } else if (window.ActiveXObject) { 
        tmpXmlHttpObject = new ActiveXObject("Microsoft.XMLHTTP");
    } else     {
    alert("Your browser does not support AJAX!");
    }
    return tmpXmlHttpObject;
}
var http = createRequestObject();