var xhr;
function pullProductsXML() {
    try {
        xhr = new ActiveXObject("Microsoft.XMLHTTP");    // Try IE
    }catch (e){
        xhr = new XMLHttpRequest();    // Other browsers
    }
    xhr.onreadystatechange = pullProductsXMLComplete;
    try {
        xhr.open('GET', '/getProductTests/pullXML.aspx', true);
        xhr.send(null);
    } catch (e) {
        //alert(e);
    }
}

function pullProductsXMLComplete() {
    if (xhr.readyState == 4) {
        // Received, OK
        if (xhr.status == 200) {
           // alert("Received:"); //xhr.responseText
        } else {
            // alert("Error code " + xhr.status);
        }
    } else {
        // Wait...
    }
}