Q:

res.send(), then res.redirect()

Why is the following not working?
res.send({
    successMessage: 'Task saved successfully.'
});
res.redirect('/');

I basically need the successMessage for AJAX requests. The redirect is necessary when the request is a standard post request (non-AJAX).
The following approach doesn't seem to be very clean to me as I don't want to care about the frontend-technology in my backend:
if(req.xhr) {
    res.contentType('json');
    res.send({
        successMessage: 'Aufgabe erfolgreich gespeichert.'
    });
} else {
    res.redirect('/');
}

A:

You can use a status code to indicate that your task was saved and then redirect. Try this:
res.status(200);
res.redirect('/');

OR
res.redirect(200, '/');

Because AJAX knows success or failure codes, so for example if you'll send 404, AJAX success function won't execute

