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Normative: Specify Date string conversion functions #848

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merged 7 commits into from
May 30, 2017
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Normative: Specify Date string conversion functions #848

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94ab5c3
Normative: Specify Date string conversion functions
littledan Mar 17, 2017
8dff62f
Move 'and'
littledan Mar 18, 2017
702d612
Delete extraneous '_result_'
littledan Mar 18, 2017
7039152
Fix GMT+-HHMM with @claudepache's text
littledan Mar 18, 2017
873e0d2
toUTCString has a comma after the day of the week
littledan Mar 22, 2017
40ad6f7
Date and time components are padded to the left by 0
littledan Mar 22, 2017
59dfec6
toUTCString swaps month and day
littledan Mar 23, 2017
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246 changes: 239 additions & 7 deletions spec.html
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Original file line number Diff line number Diff line change
Expand Up @@ -27066,7 +27066,13 @@ <h1>Date.prototype.setUTCSeconds ( _sec_ [ , _ms_ ] )</h1>
<!-- es6num="20.3.4.35" -->
<emu-clause id="sec-date.prototype.todatestring">
<h1>Date.prototype.toDateString ( )</h1>
<p>This function returns a String value. The contents of the String are implementation-dependent, but are intended to represent the &ldquo;date&rdquo; portion of the Date in the current time zone in a convenient, human-readable form.</p>
<emu-alg>
1. Let _O_ be this Date object.
1. Let _tv_ be ? thisTimeValue(_O_).
1. If _tv_ is *NaN*, return `"Invalid Date"`.
1. Let _t_ be LocalTime(_tv_).
1. Return DateString(_t_).
</emu-alg>
</emu-clause>

<!-- es6num="20.3.4.36" -->
Expand Down Expand Up @@ -27137,31 +27143,257 @@ <h1>Date.prototype.toString ( )</h1>
<p>The `toString` function is intentionally generic; it does not require that its *this* value be a Date object. Therefore, it can be transferred to other kinds of objects for use as a method.</p>
</emu-note>

<emu-clause id="sec-timestring" aoid="TimeString">
<h1>Runtime Semantics: TimeString( _tv_ )</h1>
<p>The following steps are performed:</p>
<emu-alg>
1. Assert: Type(_tv_) is Number.
1. Assert: _tv_ is not *NaN*.
1. Return String value formed by concatenating _result_, ToString(HourFromTime(_tv_)), `":"`, ToString(MinFromTime(_tv_)), `":"`, ToString(SecFromTime(_tv_)) and `" GMT"`
</emu-alg>
</emu-clause>

<emu-clause id="sec-datestring" aoid="DateString">
<h1>Runtime Semantics: DateString( _tv_, _zone_, _components_ )</h1>
<p>The following steps are performed:</p>
<emu-alg>
1. Assert: Type(_tv_) is Number.
1. Assert: _tv_ is not *NaN*.
1. Let _weekday_ be the Name of the entry in <emu-xref href="#sec-todatestring-day-names"></emu-xref> with the Number WeekDay(_t_).
1. Let _month_ be the Name of the entry in <emu-xref href="#sec-todatestring-month-names"></emu-xref> with the Number MonthFromTime(_t_).
1. Let _result_ be the String value formed by concatenating _weekday_, `" "`, _month_, `" "`, ToString(DateFromTime(_t_)), `" "`, and ToString(YearFromTime(_t_)).
</emu-alg>
<emu-table id="sec-todatestring-day-names" caption="Names of days of the week">
<table>
<tbody>
<tr>
<th>
Number
</th>
<th>
Name
</th>
</tr>
<tr>
<td>
0
</td>
<td>
`"Sun"`
</td>
</tr>
<tr>
<td>
1
</td>
<td>
`"Mon"`
</td>
</tr>
<tr>
<td>
2
</td>
<td>
`"Tue"`
</td>
</tr>
<tr>
<td>
3
</td>
<td>
`"Wed"`
</td>
</tr>
<tr>
<td>
4
</td>
<td>
`"Thu"`
</td>
</tr>
<tr>
<td>
5
</td>
<td>
`"Fri"`
</td>
</tr>
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delete extraneous result variable

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Fixed

<tr>
<td>
6
</td>
<td>
`"Sat"`
</td>
</tr>
</tbody>
</table>
</emu-table>
<emu-table id="sec-todatestring-month-names" caption="Names of months of the year">
<table>
<tbody>
<tr>
<th>
Number
</th>
<th>
Name
</th>
</tr>
<tr>
<td>
0
</td>
<td>
`"Jan"`
</td>
</tr>
<tr>
<td>
1
</td>
<td>
`"Feb"`
</td>
</tr>
<tr>
<td>
2
</td>
<td>
`"Mar"`
</td>
</tr>
<tr>
<td>
3
</td>
<td>
`"Apr"`
</td>
</tr>
<tr>
<td>
4
</td>
<td>
`"May"`
</td>
</tr>
<tr>
<td>
5
</td>
<td>
`"Jun"`
</td>
</tr>
<tr>
<td>
6
</td>
<td>
`"Jul"`
</td>
</tr>
<tr>
<td>
7
</td>
<td>
`"Aug"`
</td>
</tr>
<tr>
<td>
8
</td>
<td>
`"Sep"`
</td>
</tr>
<tr>
<td>
9
</td>
<td>
`"Oct"`
</td>
</tr>
<tr>
<td>
10
</td>
<td>
`"Nov"`
</td>
</tr>
<tr>
<td>
11
</td>
<td>
`"Dec"`
</td>
</tr>
</tbody>
</table>
</emu-table>
</emu-clause>

<emu-clause id="sec-timezoneestring" aoid="TimeZoneString">
<h1>Runtime Semantics: TimeZoneString( _tv_, )</h1>
<p>The following steps are performed:</p>
<emu-alg>
1. Assert: Type(_tv_) is Number.
1. Assert: _tv_ is not *NaN*.
1. Let _offset_ be (LocalTZA + DaylightSavingTA(_tv_)) / msPerSecond.
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This will be in conflict with #778 that drops DaylightSavingTA(tv) and change LocalTZA to take two params. We have to sort that out somehow.

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You're right; this is written against the current spec, but needs to be updated against the other one (based on whichever lands second). I guess rather than LocalTZA, we'd use LocalTimeZoneAdjustment(tz, true), right?

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Ok. this one was landed first. Then, the other one (#778) has to revise this part as well.

1. Assert: _offset_ is an integer, and -100000 &lt; _offset_ &lt; 100000.
1. If _offset_ &ge; 0, let _offsetSign_ be `"+"`; otherwise, let _offsetSign_ be `"-"`.
1. Let _offsetString_ be abs(_offset_) formatted as a four-digit number, padded to the left with zeros if necessary.
1. Let _tzName_ be an implementation-defined string, either `""` or a string of the form `" ("` _name_ `")"` where _name_ is an implementation-defined timezone name.
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Would it make sense to give a recommendation while leaving it still up to an implementation about tzName?
If it does, it can be recommended to use the canonicalized timezone in Ecma402. Perhaps, cross-referencing is not a good idea?
Just my 2 cents.

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I meant for this first patch to be purely 100% descriptive. Maybe a change like this could be in a follow-on patch?

As for making that recommendation: I don't know whether we can make it in good faith in the spec yet, as we don't know whether it's web-compatible yet. Maybe the right thing to do would be to try it out in one browser and see if it works. A good thing to know from the committee beforehand would be--would everyone be up for specifying this behavior, assuming it's web-compatible?

1. Return the String value formed by concatenating _result_, _offsetSign_, _offsetString_, and _tzName_.
</emu-alg>
</emu-clause>

<!-- es6num="20.3.4.41.1" -->
<emu-clause id="sec-todatestring" aoid="ToDateString">
<h1>Runtime Semantics: ToDateString( _tv_ )</h1>
<p>The following steps are performed:</p>
<emu-alg>
1. Assert: Type(_tv_) is Number.
1. If _tv_ is *NaN*, return `"Invalid Date"`.
1. Return an implementation-dependent String value that represents _tv_ as a date and time in the current time zone using a convenient, human-readable form.
1. Let _t_ be LocalTime(_tv_).
1. Return the String value formed by concatenating DateString(_t_), `" "`, and TimeString(_t_), TimeZoneString(_tv_).
</emu-alg>
</emu-clause>
</emu-clause>

<!-- es6num="20.3.4.42" -->
<emu-clause id="sec-date.prototype.totimestring">
<h1>Date.prototype.toTimeString ( )</h1>
<p>This function returns a String value. The contents of the String are implementation-dependent, but are intended to represent the &ldquo;time&rdquo; portion of the Date in the current time zone in a convenient, human-readable form.</p>
<emu-alg>
1. Let _O_ be this Date object.
1. Let _tv_ be ? thisTimeValue(_O_).
1. If _tv_ is *NaN*, return `"Invalid Date"`.
1. Let _t_ be LocalTime(_tv_).
1. Return the String value formed by concatenating TimeString(_t_) and TimeZoneString(_tv_).
</emu-alg>
</emu-clause>

<!-- es6num="20.3.4.43" -->
<emu-clause id="sec-date.prototype.toutcstring">
<h1>Date.prototype.toUTCString ( )</h1>
<p>This function returns a String value. The contents of the String are implementation-dependent, but are intended to represent this time value in a convenient, human-readable form in UTC.</p>
<emu-note>
<p>The intent is to produce a String representation of a date that is more readable than the format specified in <emu-xref href="#sec-date-time-string-format"></emu-xref>. It is not essential that the chosen format be unambiguous or easily machine parsable. If an implementation does not have a preferred human-readable format it is recommended to use the format defined in <emu-xref href="#sec-date-time-string-format"></emu-xref> but with a space rather than a `"T"` used to separate the date and time elements.</p>
</emu-note>
<emu-alg>
1. Let _O_ be this Date object.
1. Let _tv_ be ? thisTimeValue(_O_).
1. If _tv_ is *NaN*, return `"Invalid Date"`.
1. Return the String value formed by concatenating DateString(_tv_), `" "`, and TimeString(_tv_).
</emu-alg>
</emu-clause>

<!-- es6num="20.3.4.44" -->
Expand Down