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Update Event.timeStamp type to DOMHighResTimeStamp. #420

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merged 7 commits into from
Jul 13, 2017
Merged

Update Event.timeStamp type to DOMHighResTimeStamp. #420

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388b856
Use DOMHighResTimeStamp for Event.timeStamp.
majido Mar 8, 2017
c53e8c7
Address @domenic's feedback
majido Mar 8, 2017
4b47704
Address @annevk feedback
majido Jun 22, 2017
198fe36
Address annevk@ feedback
majido Jul 10, 2017
0ae7247
Minor corrections
majido Jul 11, 2017
f7f84d7
Add Majid Valipour to credits
majido Jul 12, 2017
3f9f333
Fix inadvertant mistake
majido Jul 12, 2017
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27 changes: 16 additions & 11 deletions dom.bs
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Original file line number Diff line number Diff line change
Expand Up @@ -70,6 +70,9 @@ urlPrefix: https://w3c.github.io/ServiceWorker/#; spec: SERVICE-WORKERS
urlPrefix: https://tc39.github.io/ecma262/#; spec: ECMASCRIPT
text: Construct; url: sec-construct; type: abstract-op
text: Realm; url: realm; type: dfn
urlPrefix: https://w3c.github.io/hr-time/#
type:typedef; urlPrefix: dom-; text: DOMHighResTimeStamp
type:dfn; text: time origin
</pre>

<pre class='link-defaults'>
Expand Down Expand Up @@ -522,7 +525,7 @@ interface Event {
readonly attribute boolean composed;

[Unforgeable] readonly attribute boolean isTrusted;
readonly attribute DOMTimeStamp timeStamp;
readonly attribute DOMHighResTimeStamp timeStamp;

void initEvent(DOMString type, optional boolean bubbles = false, optional boolean cancelable = false); // historical
};
Expand Down Expand Up @@ -628,8 +631,8 @@ algorithm below.
false otherwise.

<dt><code><var>event</var> . {{Event/timeStamp}}</code>
<dd>Returns the creation time of <var>event</var> as the number of milliseconds that
passed since 00:00:00 UTC on 1 January 1970.
<dd>Returns the <var>event</var>'s timestamp as the number of milliseconds measured relative
from the <a>time origin</a>.
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It seems to me that this term is also important for the normative definition, yet it doesn't appear there.

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relative to, no?

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Done.

</dl>

The <dfn attribute for=Event><code>type</code></dfn> attribute must
Expand Down Expand Up @@ -761,15 +764,14 @@ initialized to false.
the user agent to dispatch an <a>event</a> whose {{Event/isTrusted}} attribute is initialized to
false.

The <dfn attribute for=Event><code>timeStamp</code></dfn> attribute
must return the value it was initialized to. When an
<a>event</a> is created the attribute must be
initialized to the number of milliseconds that have passed since
00:00:00 UTC on 1 January 1970, ignoring leap seconds.
<!-- leap seconds are ignored by JavaScript too -->
The <dfn attribute for=Event><code>timeStamp</code></dfn> attribute must return the value it was
initialized to. If available, the attribute should be initialized with the high resolution time of
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Can we enumerate when it's not?

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It seems that for synthetic events this would never be available.

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What do you mean by synthetic events? If you are referring to those constructed in Javascript then that is probably correct and what for example Chrome implementation does. (BTW, I think issue #76 is proposing to make timestamp a constructor argument in which case this is not true anymore)

There may be other implementation related restrictions that makes the precise occurrence time unavailable. For example on some platforms (e.g., older Windows) there is no cross-process monotonic clock which in browsers with multi-process architecture can mean we cannot use the original timestamp. Or sometimes the driver uses a different clock and timestamp is not reliable. In such cases we end up using the closest estimation we can get. I think falling back to "creation time" is acceptable here too.

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Yeah, a synthetic event is basically a "userland" event. It would be good if we were consistent in what value it would get there (and yes, maybe at some point we allow custom values there, but that would just end up being a branch there).

I'm not really sure how to best do it though. I only have a long term vision where user interaction events are defined in much more detail and they end up initializing this attribute properly (and by default it's just creation time, whatever that means).

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Done. I now have exact details on what to use for synthetic events (i.e., use construction time).

the occurrence that the event is signaling, for example the moment when a particular user
interaction occurred. Otherwise it should be initialized with the time representing the creation
time of the <var>event</var>.
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Nit: "s/the time representing the creation time/the creation time"

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Done.


<p class=XXX>This is highly likely to change and already does not reflect implementations well.
Please see <a href=https://github.com/whatwg/dom/issues/23>dom #23</a> for more details.
<p class=note>User agents are encouraged to make the high resolution time occurrence time
available for as many events as possible in particular those related to user interaction.
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Nit: comma after "as possible"

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Done


<hr>

Expand Down Expand Up @@ -9569,6 +9571,9 @@ other chapters are defined by the <cite>UI Events</cite> specification.
<li>The propagation and canceled flags are unset when invoking
{{Event/initEvent()}} rather than after
dispatch.
<li>{{Event/timeStamp}} is no longer a {{DOMTimeStamp}} representing creation time of event as
the number of milliseconds that passed since 00:00:00 UTC on 1 January 1970, but instead a
{{DOMHighResTimeStamp}}.
</ul>


Expand Down