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...
-Boris
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.
