function makeRequest(url, id) {
        http_request = false;

        if (window.XMLHttpRequest) { // Mozilla, Safari,...
            http_request = new XMLHttpRequest();
            if (http_request.overrideMimeType) {
                http_request.overrideMimeType('text/xml');
                // Przeczytaj o tym wierszu poniżej
            }
        } else if (window.ActiveXObject) { // IE
            try {
                http_request = new ActiveXObject("Msxml2.XMLHTTP");
            } catch (e) {
                try {
                    http_request = new ActiveXObject("Microsoft.XMLHTTP");
                } catch (e) {}
            }
        }

        if (!http_request) {
            alert('Błąd podczas tworzenia instancji');
            return false;
        }
        http_request.onreadystatechange = function() { alertContents(http_request, id); };
        
        http_request.open('GET', 'includes/'+url, true);
       
        http_request.send(null);

    }

    function alertContents(http_request, id) {
        if (http_request.readyState == 4) {
            if (http_request.status == 200) {
                            
            document.getElementById(id).innerHTML = http_request.responseText;
                
            } else {
                alert('Wystąpił problem z zapytaniem.');
            }
          
        }

    }