jQuery-ajax call: async property is not working?

given to certain circumstances, I'm forced to keep page settings (Javascript-values) in the session and it has to be done right before leaving the page (I can't use cookies, since "pageSettings" can become quite large and localStorage is not an option yet ;) ). So this is how I tried it. H开发者_JS百科owever it seems that when I call the page directly again, the call of "http://blabla.com/bla" happens asynchronous, even though the async-attribute is set (I don't receive the settings of the previous call, but of the one before):

$jQ(document).ready(function () {
    $jQ(window).unload(Main.__setSessionValues);
});

var Main = {
    pageSettings: {},

    __setSessionValues: function __setSessionValues() {
        $jQ.ajax({
            type: "POST",
            async: false,
            url: "http://blabla.com/bla",
            data: {
                pageSettings: Object.toJSON(Main.pageSettings)
            }
        });
    }
};

Does anyone know what the problem might be?

thanks in advance

The code looks fine. You might try bind('beforeunload', ...) rather than unload, to grab things as early as possible. But of course, if something else also hooks beforeunload and the unload gets cancelled, your call will have been made even though you're still on the page.

Slightly off-topic, but if you can possibly find a different way to do this, I would. Firing off synchronous ajax calls when the user is trying to leave the page is not ideal.