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Add "geolocation task queue" (#87)
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‎index.html‎

Lines changed: 154 additions & 125 deletions
Original file line numberDiff line numberDiff line change
@@ -118,6 +118,9 @@ <h2>
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has received the following changes:
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</p>
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<ul>
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<li>Added the [=geolocation task source=], which handles dispatching
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position updates and errors.
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</li>
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<li>[=Request position=] only proceeds when a document is visible, or
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the document becomes visible.
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</li>
@@ -585,173 +588,180 @@ <h2>
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|successCallback:PositionCallback|, a {{PositionErrorCallback}}`?`
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|errorCallback:PositionErrorCallback|, {{PositionOptions}}
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|options:PositionOptions|, a {{boolean}} |repeats:boolean|, and
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optionally (and only if |repeats| is true) a |previous id:long|.
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optionally (and only if |repeats| is true) a |previousId:long|.
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</p>
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<ol class="algorithm">
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<li>Let |watchTasks:Set| be [=this=]'s
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{{Geolocation/[[watchTasks]]}}.
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</li>
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<li>Acquire a watch id.
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<ol>
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<li>If |previous id| was provided, let |watchId:long| be
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|previous id|; Otherwise, let |watchId:long| be an
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[=implementation-defined=] {{long}} that is greater than or equal
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to zero.
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</li>
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<li>[=Set/Append=] |watchId| to |watchTasks|.
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</li>
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<li>Return |watchId| and continue [=in parallel=].
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</li>
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</ol>
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<li>If |previousId| was provided, let |watchId:long| be |previousId|;
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Otherwise, let |watchId:long| be an [=implementation-defined=]
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{{long}} that is greater than or equal to zero.
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</li>
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<li>Do security check.
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<ol>
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<li>If the <a>environment settings object</a> is a
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<a data-cite="secure-contexts">non-secure context</a>, then:
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<ol>
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<li>[=Call back with error=] |errorCallback| and
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{{GeolocationPositionError/PERMISSION_DENIED}}.
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</li>
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<li>[=List/Remove=] |watchId| from |watchTasks|.
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</li>
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<li>Terminate this algorithm.
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</li>
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</ol>
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</li>
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</ol>
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<li>[=Set/Append=] |watchId| to |watchTasks|.
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</li>
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<li data-cite="page-visibility-2">Wait for document to become
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visible.
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<ol>
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<li>Let |document:Document| be the [=current settings object=]'s
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[=associated Document=].
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</li>
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<li>If |document:Document| is [=Document/hidden=], wait for the
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|document| to become [=Document/visible=].
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</li>
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</ol>
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<li>Let |global| be [=this=]'s [=relevant global object=].
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</li>
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<li data-tests=
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"getCurrentPosition_permission_allow.https.html, getCurrentPosition_permission_deny.https.html">
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[=Check permission=] passing |errorCallback|. If the check return
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failure:
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<li>[=Queue a global task=] using the [=geolocation task source=]
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with |global| to run the following steps [=in parallel=]:
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<ol>
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<li>[=List/Remove=] |watchId| from |watchTasks|.
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</li>
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<li>Terminate this algorithm.
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</li>
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</ol>
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</li>
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<li>
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<dfn data-local-lt=
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"acquiring a position|acquire a position">Acquire position</dfn>.
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<ol>
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<li>Let |acquisitionTime:DOMTimeStamp| be a new {{DOMTimeStamp}}
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that represents now in milliseconds, using 01 January, 1970 UTC
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as the epoch.
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</li>
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<li>If |options|.{{PositionOptions/maximumAge}} is greater than
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0, and |cachedPosition| is not null:
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<li>Do security check.
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<ol>
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<li>Let |cachedPosition:GeolocationPosition| be [=this=]'s
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{{Geolocation/[[cachedPosition]]}}.
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</li>
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<li>Let |cacheTime:long| be |acquisitionTime| minus the value
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of |options|.{{PositionOptions/maximumAge}} member.
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</li>
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<li>If |cachedPosition|'s {{GeolocationPosition/timestamp}}'s
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value is greater than |cacheTime|, and
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|cachedPosition|.{{GeolocationPosition/[[isHighAccuracy]]}}
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equals |options|.{{PositionOptions/enableHighAccuracy}}:
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<li>If the <a>environment settings object</a> is a
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<a data-cite="secure-contexts">non-secure context</a>, then:
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<ol>
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<li>[=Queue a microtask=] to invoke |successCallback|
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with |cachedPosition|.
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<li>[=Call back with error=] |errorCallback| and
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{{GeolocationPositionError/PERMISSION_DENIED}}.
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</li>
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<li>Go to <a href="#check-repeats">determine
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repetition</a> steps below.
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<li>[=List/Remove=] |watchId| from |watchTasks|.
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</li>
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<li>Terminate this algorithm.
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</li>
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</ol>
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</li>
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</ol>
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</li>
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<li>Let |timeout:Task| be a new timed [=task=] that runs in
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|options|.{{PositionOptions/timeout}} milliseconds after
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|acquisitionTime|, which performs the following sub-steps:
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<aside class="note" title="Immediate cancellation">
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<p>
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An |options|.{{PositionOptions/timeout}} value 0
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effectively runs the |timeout| task immediately.
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</p>
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</aside>
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<li data-cite="page-visibility-2">Wait for document to become
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visible.
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<ol>
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<li>If the entry for |timerId| in the [=list of active
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timers=] has been cleared, then abort these steps.
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<li>Let |document:Document| be the [=current settings
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object=]'s [=associated Document=].
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</li>
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<li>[=Call back with error=] with |errorCallback| and
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{{GeolocationPositionError/TIMEOUT}}.
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<li>If |document:Document| is [=Document/hidden=], wait for
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the |document| to become [=Document/visible=].
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</li>
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</ol>
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</li>
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<li>Let |timerId:long| be an [=implementation-defined=]
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identifier that represents |timeout|.
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</li>
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<li>Add |timerId| to the [=list of active timers=].
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<li data-tests=
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"getCurrentPosition_permission_allow.https.html, getCurrentPosition_permission_deny.https.html">
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[=Check permission=] passing |errorCallback|. If the check
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returns failure:
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<ol>
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<li>[=List/Remove=] |watchId| from |watchTasks|.
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</li>
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<li>Terminate this algorithm.
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</li>
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</ol>
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</li>
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<li>Try to acquire the device's position, optionally taking into
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consideration the value of
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|options|.{{PositionOptions/enableHighAccuracy}}:
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<li>
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<dfn data-local-lt=
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"acquiring a position|acquire a position">Acquire
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position</dfn>.
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<ol>
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<li>If acquiring a position succeeds:
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<li>Let |acquisitionTime:DOMTimeStamp| be a new
652+
{{DOMTimeStamp}} that represents now in milliseconds, using
653+
01 January, 1970 UTC as the epoch.
654+
</li>
655+
<li>If |options|.{{PositionOptions/maximumAge}} is greater
656+
than 0, and |cachedPosition| is not null:
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<ol>
706-
<li>Let |position:GeolocationPosition| be [=a new
707-
`GeolocationPosition`=] passing |acquisitionTime| and
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|options|.{{PositionOptions/enableHighAccuracy}}.
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<li>Let |cachedPosition:GeolocationPosition| be
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[=this=]'s {{Geolocation/[[cachedPosition]]}}.
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</li>
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<li>Set [=this=]'s {{Geolocation/[[cachedPosition]]}} to
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|position|.
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<li>Let |cacheTime:long| be |acquisitionTime| minus the
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value of |options|.{{PositionOptions/maximumAge}} member.
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</li>
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<li>[=Queue a microtask=] to [=invoke=] |successCallback|
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with |position|.
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<li>If |cachedPosition|'s
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{{GeolocationPosition/timestamp}}'s value is greater than
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|cacheTime|, and
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|cachedPosition|.{{GeolocationPosition/[[isHighAccuracy]]}}
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equals |options|.{{PositionOptions/enableHighAccuracy}}:
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<ol>
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<li>[=Queue a task=] on the [=geolocation task
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source=] with a step that [=invokes=]
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|successCallback| with |cachedPosition|.
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</li>
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<li>Go to <a href="#check-repeats">determine
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repetition</a> steps below.
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</li>
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</ol>
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</li>
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</ol>
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</li>
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<li>If acquiring a position fails:
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<li>Let |timeout:Task| be a new timed [=task=] that runs in
682+
|options|.{{PositionOptions/timeout}} milliseconds after
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|acquisitionTime|, which performs the following sub-steps:
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<aside class="note" title="Immediate cancellation">
685+
<p>
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An |options|.{{PositionOptions/timeout}} value 0
687+
effectively runs the |timeout| task immediately.
688+
</p>
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</aside>
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<ol>
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<li>[=Call back with error=] passing |errorCallback| and
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{{GeolocationPositionError/POSITION_UNAVAILABLE}}.
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<li>If the entry for |timerId| in the [=list of active
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timers=] has been cleared, then abort these steps.
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</li>
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<li>[=Call back with error=] with |errorCallback| and
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{{GeolocationPositionError/TIMEOUT}}.
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</li>
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</ol>
724698
</li>
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<li>Let |timerId:long| be an [=implementation-defined=]
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identifier that represents |timeout|.
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</li>
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<li>Add |timerId| to the [=list of active timers=].
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</li>
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<li>Try to acquire the device's position, optionally taking
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into consideration the value of
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|options|.{{PositionOptions/enableHighAccuracy}}:
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<ol>
708+
<li>If acquiring a position succeeds:
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<ol>
710+
<li>Let |position:GeolocationPosition| be [=a new
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`GeolocationPosition`=] passing |acquisitionTime| and
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|options|.{{PositionOptions/enableHighAccuracy}}.
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</li>
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<li>Set [=this=]'s {{Geolocation/[[cachedPosition]]}}
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to |position|.
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</li>
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<li>[=Queue a task=] on the [=geolocation task
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source=] with a step that [=invokes=]
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|successCallback| with |position|.
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</li>
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</ol>
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</li>
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<li>If acquiring a position fails:
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<ol>
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<li>[=Call back with error=] passing |errorCallback|
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and
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{{GeolocationPositionError/POSITION_UNAVAILABLE}}.
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</li>
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</ol>
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</li>
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</ol>
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</li>
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<li>Clear |timerId| from the [=list of active timers=].
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</li>
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</ol>
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</li>
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<li>Clear |timerId| from the [=list of active timers=].
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</li>
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</ol>
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</li>
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<li>
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<span id="check-repeats">Determine repetition</span>.
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<ol>
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<li>If |repeats| is false:
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<li>
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<span id="check-repeats">Determine repetition</span>.
735739
<ol>
736-
<li>[=List/Remove=] |watchId| from |watchTasks|.
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<li>If |repeats| is false:
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<ol>
742+
<li>[=List/Remove=] |watchId| from |watchTasks|.
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</li>
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<li>Terminate this algorithm.
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</li>
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</ol>
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</li>
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<li>Terminate this algorithm.
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</ol>
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</li>
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<li>Wait for a significant change of geographic position. What
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constitutes a significant change of geographic position is left
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to the implementation. User agents MAY impose a rate limit on
753+
the frequency position changes.
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</li>
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<li>If |watchTasks| [=list/contain|contains=] |watchId|, then:
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<ol>
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<li>[=Request position=] passing |successCallback|,
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|errorCallback|, |options|, |repeats|, and |watchId|.
739759
</li>
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</ol>
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</li>
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</ol>
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</li>
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<li>Wait for a significant change of geographic position. What
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constitutes a significant change of geographic position is
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[=implementation-defined|left to the implementation=]. A user agent
747-
MAY impose a rate limit on the frequency of position changes.
748-
</li>
749-
<li>If |watchTasks| [=list/contain|contains=] |watchId|, then:
750-
<ol>
751-
<li>[=Request position=] passing |successCallback|,
752-
|errorCallback|, |options|, |repeats|, and |watchId|.
753-
</li>
754-
</ol>
764+
<li>Return |watchId|.
755765
</li>
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</ol>
757767
</section>
@@ -795,7 +805,8 @@ <h2>
795805
{{GeolocationPositionError}} instance whose
796806
{{GeolocationPositionError/code}} attribute is initialized to |code|.
797807
</li>
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<li>[=Invoke=] |callback| with |error|.
808+
<li>[=Queue a task=] on the [=geolocation task source=] with a step
809+
that [=invokes=] |callback| with |error|.
799810
</li>
800811
</ol>
801812
</section>
@@ -917,6 +928,24 @@ <h2>
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</tr>
918929
</table>
919930
</section>
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<section>
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<h2>
933+
Task sources
934+
</h2>
935+
<p>
936+
The following [=task source=] is defined by this specifications.
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</p>
938+
<dl>
939+
<dt>
940+
The <dfn>geolocation task source</dfn>
941+
</dt>
942+
<dd>
943+
Used by this specification to queue up non-blocking
944+
{{PositionCallback}} and {{PositionErrorCallback}} when performing
945+
[=request position|position requests=].
946+
</dd>
947+
</dl>
948+
</section>
920949
</section>
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<section id="coordinates_interface" data-dfn-for="GeolocationCoordinates">
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<h2>

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