Question

I would like doing in javascript (jQuery):

if (close tab || close window) {
   $.ajax({
        type: "POST",
        url: "process_form.php",
        data: dataString

        });
}

Is this possible without message if you want leave page etc?

Answer 1

There is only one useful event you can rely on for that reason, onbeforeunload.

window.onbeforeunload = function() {
    $.ajax({});
};

Unless you explicitly return false from that event, there is no message to the user. You might want to create a synchronised request anyway, because the browser will not wait for an asyncronous request to finish.