function trwa_ladowanie() {
  return '<div id="ladowanie"><b>Proszę czekać</b><br>Trwa ładowanie strony...<br><br><img src="images/loading.gif" alt="loading"></div>';
}

var http_request = false;
  
function makeRequest(object, url) {
    document.getElementById(object).innerHTML = trwa_ladowanie();
    http_request = false;
    if (window.XMLHttpRequest) { // Mozilla, Safari,...
        http_request = new XMLHttpRequest();
        if (http_request.overrideMimeType) {
            http_request.overrideMimeType('text/xml');
        }
    } 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('Poddaje się :( Nie mogę stworzyć instancji obiektu XMLHTTP');
        return false;
    }
    http_request.onreadystatechange = function() { changeContents(object, http_request, url); };
    http_request.open('GET', url, true);
    http_request.send(null);
}

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

function changeContents(object, http_request, url) {
    if (http_request.readyState == 4) {
        if (http_request.status == 200) {
            change_html(object, http_request.responseText);
        } else {
            alert('Wystąpił problem z zapytaniem AJAX: ' + url + "\n\nkod: "+ http_request.status);
        }
    }
}

function change_html(object, html) {
  if (document.getElementById) {
    document.getElementById(object).innerHTML = html;
  } else if (document.layers && document.layers[object] != null) {
    document.layers[object].innerHTML = html;
  } else if (document.all) {
    document.all[object].innerHTML = html;
  }
  return false;
}