[Originally sent to www-dom, re-sent here on Björn's request. Including
extra questions from [EMAIL PROTECTED]
Hi,
I have a request for clarification regarding the behaviour of capturing
events.
Opera has implemented capture of load events in the document, meaning that
an event listener added with
window.addEventListener('load', func, true);
would run for every load event on IMG, SCRIPT, LINK rel="stylesheet" etc.
in the document.
This is also implemented in Safari but not supported in Mozilla until
recently (see bug 331306 - [1])
While we think Opera's/Safari's implementation is correct according to the
spec, a number of sites out there rely on Mozilla's bug and expect such an
event listener to run only once.
Mozilla developers have proposed a solution in bug 335251 [2]. They
suggest that load events should not propagate to the "window" object in
the browser's JavaScript environment.
Pros of Mozilla's suggestion:
- it's backwards compatible with existing content
Cons:
- we introduce an inconsistency to the whole event listener model that
means for example these two will mean very different things..
window.addEventListener('click', func, true); // runs for any click event
window.addEventListener('load', func, true); // runs once only
It is not clear from the DOM Events spec how the "window" object fits into
the capturing/bubbling. Could this be clarified? Which behaviour should be
considered correct per the spec?
João's questions:
- is the window considered as a target in the entire event capturing and
bubbling phases ?
* in Gecko yes, in Opera no.
- should events registered to the window have the document as target ?
* both in Gecko and Opera yes.
- should capturing of load events be supported too when registering a
capturing event listener in the window ?
* in Opera yes, in Gecko no as consequence of their 'fix'
The ecmascript binding needs clarification in this regard.
[1] https://bugzilla.mozilla.org/show_bug.cgi?id=331306
[2] https://bugzilla.mozilla.org/show_bug.cgi?id=335251
Commentary:
http://my.opera.com/hallvors/blog/2006/12/23/firechicken
--
Hallvord R. M. Steen
Core QA JavaScript tester, Opera Software
http://www.opera.com/
Opera - simply the best Internet experience
