1608498 - Weird behavior of webkit-prefixed transition/animation events wrt case

Status: RESOLVED DUPLICATE of bug 1607918

(Core :: DOM: Events, defect)

Description

[Boris Zbarsky [:bzbarsky]]

Consider this testcase:

  <script>
    var el = document.createElement("div");
    el.addEventListener("webkitAnimationEnd", () => console.log("cased"));
    el.addEventListener("webkitanimationend", () => console.log("lowercase"));
    el.dispatchEvent(new AnimationEvent("webkitAnimationEnd"));
  </script>

In Firefox, that logs both "cased" and "lowercase" to the console. In Chrome and Safari it just logs "cased". The same happens for webkitAnimationIteration, webkitAnimationStart, webkitTransitionEnd.

I expect that's because https://searchfox.org/mozilla-central/rev/ba4fab1cc2f1c9c4e07cdb71542b8d441707c577/dom/events/EventNameList.h#519-537 map two different names to the same event type, and the dispatch is done by event type.

What I am not quite sure about is why we need these all-lowercase bits guarded on MESSAGE_TO_EVENT at all. Can't we just define the properly-cased versions and use [BinaryName] to map the all-lowercase IDL bits to the correct-cased getters/setters?

Comment 1

[Boris Zbarsky [:bzbarsky]]

This was mentioned near the end of https://groups.google.com/a/chromium.org/d/msg/blink-dev/4Fidt4JqkTk/MNJiPs8cCQAJ

Comment 2

[smcgruer]

Hey Boris; thanks for filing this, but I think it is a dupe of https://bugzilla.mozilla.org/show_bug.cgi?id=1607918 :)

Comment 3

[Boris Zbarsky [:bzbarsky]]

Indeed. Hadn't done the search and didn't know a bug was already filed. ;)