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Re: [whatwg] DOM Events Proposal: EventListenerOptions 'mayCancel' for improved scroll performance

From: Philip Jägenstedt <philipj@opera.com>
Date: Thu, 9 Jul 2015 15:49:44 +0200
Message-ID: <CAMQvoCnsOPo4wvpNB+8BPEKeK8WfaEExrOKM3D7Du2UnOheT8Q@mail.gmail.com>
To: Rick Byers <rbyers@chromium.org>
Cc: WHATWG <whatwg@whatwg.org>, James Ross <w3c-20040125@james-ross.co.uk>
On Thu, Jul 9, 2015 at 3:44 PM, Rick Byers <rbyers@chromium.org> wrote:
> On Thu, Jul 9, 2015 at 9:39 AM, Rick Byers <rbyers@chromium.org> wrote:
>>
>>
>> On Thu, Jul 9, 2015 at 9:05 AM, James Ross <w3c-20040125@james-ross.co.uk>
>> wrote:
>>>
>>> > Date: Thu, 9 Jul 2015 14:42:07 +0200
>>> > From: philipj@opera.com
>>> >
>>> > I think this looks like a very promising approach. Would there be any
>>> > way to feature detect support for EventListenerOptions as the third
>>> > argument? It seems like a problem that addEventListener(type,
>>> > callback, { mayCancel: false }) would be treated as
>>> > addEventListener(type, callback, true) in existing browsers.
>>>
>>>
>>> http://rbyers.github.io/EventListenerOptions/EventListenerOptions.html#extensions-to-the-event-interface
>>> and
>>> http://rbyers.github.io/EventListenerOptions/EventListenerOptions.html#examples
>>> example 2 are intended to cover this.
>>
>>
>> Right, thanks.  What I've suggested is kind of weird though.  Olli raises
>> a good point that we should discuss general dictionary-member feature
>> detection patterns in the abstract before committing to something like this.
>> I'd love other opinions / ideas on the bug.
>
>
> I should perhaps add that I'd hope developers don't really need to use the
> pattern in example #2 explicitly.  Instead I expect they'd mostly rely on a
> simple polyfill (which I'll take an initial crack at writing once the API
> shape settles down a bit).

I see, the answer is getSupportedListenerOptions(). Seems slightly
peculiar, but would work. Should be on EventTarget if anything,
though.
Received on Thursday, 9 July 2015 13:50:18 UTC

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