Re: [DOM3Events] Pointer Events request to change DOM 3 Events "button" type

* Jacob Rossi wrote:
>From: Bjoern Hoehrmann <>
>> proposes "In order
>> to facilitate differentiating button state transitions in any pointer
>> event (and not just pointerdown and pointerup), the button property
>> takes on a new value when no mouse buttons are depressed" specifically
>> the value -1 would be for "Mouse move with no buttons pressed". So, for
>> 'mousemove' with no button pressed you will get MouseEvent.button == 0,
>> while for "pointer events" you get MouseEvent.button == -1?
>Trusted mouse* events will not change (preserving compat).  So for a mousemove,
>you'll get 0. But for pointermove you would get -1.

Expressing the same state through the same interface using two mutually
exclusive attribute values strikes me as bad interface design. So does
using the value -1 for this more generally, and using magic numbers here
more generally; using a bitmask in `MouseEvent.buttons` is not much of
an improvement, but given `MouseEvent.buttons`, I do not see why using
the `-1` value in `MouseEvent.button` is necessary or desirable. Perhaps
the Pointer Events Working Group could make a better argument for this
design than pointing out that they "want it"? Then we could come up with
alternatives and evaluate them.
Björn Höhrmann · ·
Am Badedeich 7 · Telefon: +49(0)160/4415681 ·
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Received on Tuesday, 22 January 2013 12:04:01 UTC