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editorial: Remove the definition of "epoch-relative timestamp". #153

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merged 3 commits into from
Mar 21, 2023
Merged

editorial: Remove the definition of "epoch-relative timestamp". #153

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0d8884b
Remove the definition of "epoch-relative timestamp".
jyasskin Mar 20, 2023
08bc1fe
Re-add the paragraph about DOMHighResTimeStamp resolution.
jyasskin Mar 20, 2023
20c73a0
Spell out "microseconds".
jyasskin Mar 21, 2023
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40 changes: 10 additions & 30 deletions index.html
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Expand Up @@ -648,28 +648,6 @@ <h3>
the [=monotonic clock/unsafe current time=] of the <a>monotonic
clock</a>.
</p>
<p>
To get an <dfn data-export="">epoch-relative timestamp</dfn>,
optionally with a [=moment=] on the [=wall clock=] |time:moment on the
wall clock|:
</p>
<ol class="algorithm">
<li>If |time| was not passed, set |time| to the [=wall clock=]'s [=wall
clock/unsafe current time=].
</li>
<li>Assert: |time| is greater than or equal to 1 January 1970 00:00:00
UTC.
</li>
<li>Return the number of milliseconds from the [=Unix epoch=] to
|time|: where each day is comprised of 86,400 seconds, each of which is
1000 milliseconds long (i.e., don't account for leap seconds).
</li>
</ol>
<p class="note">
A {{DOMHighResTimeStamp}} is a double. Therefore, using it to represent
an [=epoch-relative timestamp=], e.g. for the purpose of comparing it
with <a>Date.now()</a>, might lose sub-millisecond precision.
</p>
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</section>
<section id="sec-domhighrestimestamp">
<h3>
Expand All @@ -689,6 +667,12 @@ <h3>
accurate enough to allow measurement while preventing timing attacks -
see <a href="#clock-resolution"></a> for additional considerations.
</p>
<p class="note">
A {{DOMHighResTimeStamp}} is a {{double}}, so it can only represent an
epoch-relative time&mdash;the number of milliseconds from the [=Unix
epoch=] to a [=moment=]&mdash;to a finite resolution. For [=moments=] in
2023, that resolution is approximately 0.2µs.
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</p>
</section>
<section>
<h3>
Expand All @@ -704,14 +688,10 @@ <h3>
</p>
</aside>
<p>
A {{EpochTimeStamp}} represents the number of milliseconds from a given
time to 01 January, 1970 00:00:00 UTC, excluding leap seconds.
Specifications that use this type define how the number of milliseconds
are interpreted. An {{EpochTimeStamp}} is initialized by calling
[=epoch-relative timestamp=] with no arguments, which defaults to the
current time. Specifications that require a different relative time can
call [=epoch-relative timestamp=] with a [=moment=] from the [=wall
clock=] as an argument, if needed.
A {{EpochTimeStamp}} represents an integral number of milliseconds from
the [=Unix epoch=] to a given [=moment=] on the [=wall clock=],
excluding leap seconds. Specifications that use this type define how the
number of milliseconds are interpreted.
</p>
</section>
<section id="sec-performance" data-dfn-for="Performance">
Expand Down