804148 - DomContentLoaded does not trigger CSS transitions

Status: RESOLVED INVALID

(Core :: CSS Parsing and Computation, defect)

Description

[Tobias Tom]

Attachment: not-working.html

User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_8_2) AppleWebKit/536.26.14 (KHTML, like Gecko) Version/6.0.1 Safari/536.26.14

Steps to reproduce:

Start a transition as soon as the DOMContentLoaded event was fired.


Actual results:

The transition is never stared and the element is directly placed at the final position.


Expected results:

The page should have started the transition as soon as the DOMContentLoaded was fired.

Comment 1

[Tobias Tom]

Attachment: Working example.

Comment 2

[Cork]

This is WFM in current nightly (19), can reproduce in release (16).

Comment 3

[Cork]

Disregard comment 2, I can only get it working intermittently in nightly (succeeded every time yesterday). So this is obviously not fixed

Comment 4

[[:Aleksej]]

Nightly linux-x86_64:

Doesn't work with either testcase (the text is partly outside of the page — transitions not supported?): 2011-02-28-03…2011-05-04-03

Confirmed: 2011-05-05-03….

https://hg.mozilla.org/mozilla-central/pushloghtml?startdate=2011-05-04+01&enddate=2011-05-05+04

Comment 5

[Ioana (away)]

Confirmed with the attached test cases on:
Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:19.0) Gecko/19.0 Firefox/19.0 (20121030030633)

Comment 6

[Boris Zbarsky [:bzbarsky]]

The behavior is correct per spec.  DOMContentLoaded can easily fire before any layout has been done, in which case there is no computed style determination until _after_ the event, so there is never a "pre-change" state here.

This is the same as what you get if you create a new element, put it in the DOM, then immediately set its className (maybe even off a timeout).  You might or might not get a transition depending on the race between the first time the style is computed and the className set.

This is, unfortunately, a known issue with the transitions spec.  You can work around by explicitly computing the relevant style on the element before you try to start the transition....