Testing this shows that IE9 doesn't fire a progress event for the
transition that is of interest for the use case. That is, when the script
transitions to "loaded", there's no event. Once the script has been
evaluated, there is a (rather useless) progress event for the transition
to "complete". The interesting transition to "loaded" can only be
observed
by polling. Sigh. :-(
Demo: http://hsivonen.iki.fi/test/moz/script-readystate.html
You're correct about this not working in IE9b. But it would seem that it's
a
regression, as I just checked in IE6-8, and it does indeed fire the
`onreadystatechange` event on the "loaded" state. I'm going to file a bug
in
the IE9 feedback system to ask them to address that regression.
Here's my test: http://test.getify.com/ie-script-readystate/
UPDATE: IE9 RC1 came out today, and this regression is fixed.
`readyState=loaded` does fire the `onreadystatechange` handler as expected.
Good news for the support of `readyState` proposal, I think.
*HOWEVER*, in IE6-8 (and I would assume IE9 once they address that
regression), there's still a wrinkle with being able to rely on the
"loaded"
readyState event. If the script is already in the cache, it appears that
IE
does *not* fire the "loaded" readyState event. Obviously, this is quite
unfortunate, since it means that polling would still be a necessary piece
of
the puzzle for IE.
Turns out I was completely wrong on this. `readyState=loaded` fires fine
with cached items. My test code has a race-condition in it that was masking
the correct behavior.
So, at this point, I can verify (at least in my tests), that `readyState`
works fine (without polling) in at least IE6-IE9. This means polling is not
necessary to support that functionality in IE. Good news on both fronts.
--Kyle
