var xmlHttp = createXmlHttpRequestObject();

function createXmlHttpRequestObject() {
    var xmlHttp;

    if(window.ActiveXObject) {
        try {
            xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
        } catch (e) {
            xmlHttp = false;
        }
    } else {
        try {
            xmlHttp = new XMLHttpRequest();
        } catch (e) {
            xmlHttp = false;
        }
    }

    if(!xmlHttp)
        alert("Error creating the XMLHttpRequest object.");
    else
        return xmlHttp;
}

function get_new_products_data() {
    if(xmlHttp.readyState == 4 || xmlHttp.readyState == 0) {
        xmlHttp.open("GET", "new_products_ajax.php", true);
        xmlHttp.onreadystatechange = handleServerResponse;
        xmlHttp.send(null);
    }

    setTimeout('get_new_products_data()', 30000);
}

function handleServerResponse() {
}