addOnUnload events fire on windowon.unload at which time which Firefox is unstable

[sjmiles]

At window.onunload time Firefox appears to be at an odd state, some objects are not accessible from some scopes, and Firebug is confused.

window.onbeforeunload seems more reliable. IE still needs to use onunload because it has it's own issues which are documented inline in hostenv_browser.js.

It's potentially confusing to have addOnUnload really do addOnBeforeUnload on some browsers, but I'm not sure users care. If you just want to "do something at the end" it should be ok. If you really want one of the specific events, you can connect directly.

[sjmiles]

(In [9367]) Change addOnUnload events to fire at window.onbeforeunload (except on IE), refs #3567.

[James Burke]

This page seems to indicate that caching will be disabled if there is a window.onbeforeunload handler: ​http://ajaxian.com/archives/newsvine-live-evergreen-is-forever

It may just mean the in-memory cache is not used (for things like fast back rendering), but some references on the web seem to indicate that it also affects the normal browser cache.

I'm going to reopen for 0.9, so that we can verify if it has an effect on caching. I'll assign the bug to me (at least the part about checking the affect on the cache).

[James Burke]

Talked with Alex about it. He thought it just affected the "fastback" back button cache. I'll push to 1.0 and follow up with sjmiles on the motivation for this change.

[James Burke]

This page the bfcache is affected by any type of unload registration:

​http://developer.mozilla.org/en/docs/Using_Firefox_1.5_caching

[James Burke]

It seems this is only affects the back/forward cache and not the normal cache, given the info above, so re-closing this ticket.