On 06/12/2012 08:56 PM, Boris Zbarsky wrote:
On 6/12/12 6:30 AM, James Graham wrote:
Based on some tests ([1]-[5]), it seems that WebKit seems to cancel the
navigation in the unload handler always, Opera seems to always carry out
the navigation in the unload handler, and Gecko seems to follow WebKit
in the cross-origin case and Opera in the same-origin case. In all cases
the unload handler is only called once.
[1] http://hoppipolla.co.uk/tests/navigation/003.html
[2] http://hoppipolla.co.uk/tests/navigation/004.html
[3] http://hoppipolla.co.uk/tests/navigation/005.html
[4] http://hoppipolla.co.uk/tests/navigation/006.html
[5] http://hoppipolla.co.uk/tests/navigation/007.html
For what it's worth, we initially tried to do what you say WebKit does
but ran into web compat issues. See
https://bugzilla.mozilla.org/show_bug.cgi?id=371360 for the original bug
where we blocked all navigation during unload and
https://bugzilla.mozilla.org/show_bug.cgi?id=409888 for the bug where we
changed to the current behavior. I believe the spec says what it says
based on our implementation experience here...
Hmm, so I wonder if the WebKit people consider it a problem that they
don't pass the tests in those bug reports. I couldn't find any of the
original sites still responding, so it's hard to know if there is still
a compat. problem here. If there isn't, the greater conceptual
simplicity of the WebKit model is quite appealing.
P.S. Opera's behavior is not quite as simple as you describe: as far as
I can tell it depends on whether the unload is happening due to the user
typing something in the url bar or due to the user clicking a link, say.
That seems to be true. On the other hand it appears that gecko will
still respect navigation from unload even if the unload was triggered by
explicit user interaction (e.g. by editing the address bar), as long as
all the origins match, so you can end up at a different page to the one
you expected. That is very surprising behaviour (although I see that you
can argue that it is possible in other ways).
