[pointerevents] Behaviour of dblclicks is not specified

IvanSanchez has just created a new issue for 

== Behaviour of dblclicks is not specified ==
I'm a maintainer of Leaflet, and after fixing bug 
https://github.com/Leaflet/Leaflet/issues/5180 , I must complain about
 `dblclick`s in browsers which support `PointerEvent`s.

As far as I'm aware, the current state of affairs when it comes to 
firing `dblclick` events is:

| Browser        | Fires `dblblick` when double-clicking with a mouse
  | Fires `dblclick` when double-tapping a touchscreen | Supports 
`PointerEvent`s |
| -------------- | ------------- | ------------- | ------------- |
| IE10, IE11     | Yes           | Yes           | Yes           |
| Edge           | Yes           | No            | Yes           |
| Firefox (v50)  | Yes           | No            | No            |
| Chrome (v<55)  | Yes           | No            | No            |
| Chrome (v>=55) | Yes           | Yes           | Yes           |
| Safari         | Yes           | No            | No            |

This makes polyfilling `dblclick` behaviour a hard issue (and one that
 requires browser sniffing which, as we know, is a Bad Idea™). As far 
as I'm aware, Leaflet is the only library that polyfills `dblclick`s 
for `PointerEvent`s; [https://github.com/jquery/PEP/](jquery-PEP) does

Part of the fault is attributable to the current redaction of the 
`dblclick` event in 
(emphasis mine):

> A user agent MUST dispatch this event when the primary **button** of
 a pointing device is clicked twice over an element. The **definition 
of a double click depends on the environment configuration**, except 
that the event target MUST be the same between mousedown, mouseup, and

That was written way before `TouchEvent`s were defined or implemented,
 so browser vendors can either stick to the wording (like Edge) or to 
the spirit (like Chrome, IE10/IE11).

I hereby request that UAs should behave **consistently** about firing 
`dblclick`s, and that this should be specified and documented. Either 
fire `dblclick`s only with a mouse, or fire `dblclick`s with any 
pointer type (I'd slightly prefer the later).

This probably depends on 
https://github.com/w3c/pointerevents/issues/100 , but is a different 

Please view or discuss this issue at 
https://github.com/w3c/pointerevents/issues/171 using your GitHub 

Received on Thursday, 19 January 2017 15:34:23 UTC