//Gets the browser specific XmlHttpRequest Object
function getXmlHttpRequestObject() {
    if (window.XMLHttpRequest) {
        return new XMLHttpRequest();
    } else if(window.ActiveXObject) {
        return new ActiveXObject("Microsoft.XMLHTTP");
    } else {
        alert("Om deze site te bekijken heeft u een ajax-compatible browser nodig");
    }
}
var searchReq = getXmlHttpRequestObject();

//Starts the AJAX request.
function getImages(action, cat_id, id) {
    if (searchReq.readyState == 4 || searchReq.readyState == 0) {
        searchReq.open("GET", '/_ajax/image.php?action=' + action + '&cat_id=' + cat_id , true);

        searchReq.onreadystatechange = handleGetImages; 
        searchReq.send(null);	
    }  
}

//Called when the AJAX response is returned.
function handleGetImages() {
    if (searchReq.readyState == 4) {
        var ss = document.getElementById('photos')
        ss.innerHTML = '';
        if (searchReq.responseText != '') {
            var str = searchReq.responseText.split("<endparam>");
            ss.innerHTML += str[1];
            LoadImage(str[0]);
        }
    }
}