It’s not specifically a Ruby thing, but a Rails4 Turbolinks one.
Since turbolinks does not do real page reloads, it triggers events like
page:fetch, page:load, page:change, etc. But I can’t find one, that
is capable of interrupting the click. I’m looking for something that is
a BeforeUnLoad event in normal cases. Does someone know if there
is such one? page:fetch seemd to me the one, but capturing it and
returning false does not stop the event.