-
Notifications
You must be signed in to change notification settings - Fork 0
Expand file tree
/
Copy pathspec.emu
More file actions
1330 lines (1272 loc) · 69.4 KB
/
Copy pathspec.emu
File metadata and controls
1330 lines (1272 loc) · 69.4 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
<!DOCTYPE html>
<meta charset="utf8">
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/highlight.js/8.4/styles/github.min.css">
<pre class="metadata">
title: Intl.DateTimeFormat Alignment With Other Standards
stage: 1
contributors: Eemeli Aro
location: https://tc39.es/proposal-intl-datetime-alignment/
</pre>
<emu-intro id="intro">
<h1>Introduction</h1>
<p>An explainer for this proposal is available at <a href="https://github.com/tc39/proposal-intl-datetime-alignment">github.com/tc39/proposal-intl-datetime-alignment</a>.</p>
</emu-intro>
<emu-clause id="datetimeformat-objects" number="11">
<h1>DateTimeFormat Objects</h1>
<emu-clause id="sec-intl-datetimeformat-constructor">
<h1>The Intl.DateTimeFormat Constructor</h1>
<emu-clause id="sec-createdatetimeformat" type="abstract operation" oldids="sec-initializedatetimeformat,sec-todatetimeoptions" number="2">
<h1>
CreateDateTimeFormat (
_newTarget_: a constructor,
_locales_: an ECMAScript language value,
_options_: an ECMAScript language value,
_required_: ~date~, ~time~, or ~any~,
_defaults_: ~date~, ~time~, or ~all~,
): either a normal completion containing a DateTimeFormat object or a throw completion
</h1>
<dl class="header">
</dl>
<emu-alg>
1. Let _dateTimeFormat_ be ? OrdinaryCreateFromConstructor(_newTarget_, *"%Intl.DateTimeFormat.prototype%"*, « [[InitializedDateTimeFormat]], [[Locale]], [[Calendar]], [[NumberingSystem]], [[TimeZone]], [[HourCycle]], [[DateStyle]], [[TimeStyle]], [[DateTimeFormat]], [[BoundFormat]] »).
1. Let _specialOptions_ be the Record { [[Hour12]]: *undefined* }.
1. Let _modifyResolutionOptions_ be a new Abstract Closure with parameters (_options_) that captures _specialOptions_ and performs the following steps when called:
1. Set _specialOptions_.[[Hour12]] to _options_.[[hour12]].
1. Remove field [[hour12]] from _options_.
1. If _specialOptions_.[[Hour12]] is not *undefined*, set _options_.[[hc]] to *null*.
1. Let _optionsResolution_ be ? ResolveOptions(%Intl.DateTimeFormat%, %Intl.DateTimeFormat%.[[LocaleData]], _locales_, _options_, « ~coerce-options~ », _modifyResolutionOptions_).
1. Let _hour12_ be _specialOptions_.[[Hour12]].
1. Set _options_ to _optionsResolution_.[[Options]].
1. Let _resolvedLocale_ be _optionsResolution_.[[ResolvedLocale]].
1. Set _dateTimeFormat_.[[Locale]] to _resolvedLocale_.[[Locale]].
1. Let _resolvedCalendar_ be _resolvedLocale_.[[ca]].
1. Set _dateTimeFormat_.[[Calendar]] to _resolvedCalendar_.
1. Set _dateTimeFormat_.[[NumberingSystem]] to _resolvedLocale_.[[nu]].
1. Let _resolvedLocaleData_ be _resolvedLocale_.[[LocaleData]].
1. If _hour12_ is *true*, then
1. Let _hc_ be _resolvedLocaleData_.[[hourCycle12]].
1. Else if _hour12_ is *false*, then
1. Let _hc_ be _resolvedLocaleData_.[[hourCycle24]].
1. Else,
1. Assert: _hour12_ is *undefined*.
1. Let _hc_ be _resolvedLocale_.[[hc]].
1. If _hc_ is *null*, set _hc_ to _resolvedLocaleData_.[[hourCycle]].
1. Let _timeZone_ be ? Get(_options_, *"timeZone"*).
1. If _timeZone_ is *undefined*, then
1. Set _timeZone_ to SystemTimeZoneIdentifier().
1. Else,
1. Set _timeZone_ to ? ToString(_timeZone_).
1. If IsTimeZoneOffsetString(_timeZone_) is *true*, then
1. Let _parseResult_ be ParseText(StringToCodePoints(_timeZone_), |UTCOffset|).
1. Assert: _parseResult_ is a Parse Node.
1. If _parseResult_ contains more than one |MinuteSecond| Parse Node, throw a *RangeError* exception.
1. Let _offsetNanoseconds_ be ParseTimeZoneOffsetString(_timeZone_).
1. Let _offsetMinutes_ be _offsetNanoseconds_ / (6 × 10<sup>10</sup>).
1. Assert: _offsetMinutes_ is an integer.
1. Set _timeZone_ to FormatOffsetTimeZoneIdentifier(_offsetMinutes_).
1. Else,
1. Let _timeZoneIdentifierRecord_ be GetAvailableNamedTimeZoneIdentifier(_timeZone_).
1. If _timeZoneIdentifierRecord_ is ~empty~, throw a *RangeError* exception.
1. Set _timeZone_ to _timeZoneIdentifierRecord_.[[PrimaryIdentifier]].
1. Set _dateTimeFormat_.[[TimeZone]] to _timeZone_.
1. Let _formatOptions_ be a new Record.
1. Set _formatOptions_.[[hourCycle]] to _hc_.
1. Let _hasExplicitFormatComponents_ be *false*.
1. For each row of <emu-xref href="#table-datetimeformat-components"></emu-xref>, except the header row, in table order, do
1. Let _propertyKey_ be the name given in the Property column of the current row.
1. If _propertyKey_ is *"fractionalSecondDigits"*, then
1. Let _value_ be ? GetNumberOption(_options_, *"fractionalSecondDigits"*, 1, 3, *undefined*).
1. Else,
1. Let _values_ be a List whose elements are the strings given in the Values column of the current row.
1. Let _value_ be ? GetOption(_options_, _propertyKey_, ~string~, _values_, *undefined*).
1. Set _formatOptions_.[[<_propertyKey_>]] to _value_.
1. If _value_ is not *undefined*, then
1. Set _hasExplicitFormatComponents_ to *true*.
1. Let _formatMatcher_ be ? GetOption(_options_, *"formatMatcher"*, ~string~, « *"basic"*, *"best fit"* », *"best fit"*).
1. Let _dateStyle_ be ? GetOption(_options_, *"dateStyle"*, ~string~, « *"full"*, *"long"*, *"medium"*, *"short"* », *undefined*).
1. Set _dateTimeFormat_.[[DateStyle]] to _dateStyle_.
1. Let _timeStyle_ be ? GetOption(_options_, *"timeStyle"*, ~string~, « *"full"*, *"long"*, *"medium"*, *"short"* », *undefined*).
1. Set _dateTimeFormat_.[[TimeStyle]] to _timeStyle_.
1. If _dateStyle_ is not *undefined* or _timeStyle_ is not *undefined*, then
1. If _hasExplicitFormatComponents_ is *true*, then
1. Throw a *TypeError* exception.
1. If _required_ is ~date~ and _timeStyle_ is not *undefined*, then
1. Throw a *TypeError* exception.
1. If _required_ is ~time~ and _dateStyle_ is not *undefined*, then
1. Throw a *TypeError* exception.
1. Let _styles_ be _resolvedLocaleData_.[[styles]].[[<_resolvedCalendar_>]].
1. Let _bestFormat_ be DateTimeStyleFormat(_dateStyle_, _timeStyle_, _styles_).
1. Else,
1. Let _needDefaults_ be *true*.
1. If _required_ is ~date~ or ~any~, then
1. For each property name _propertyKey_ of « *"weekday"*, *"year"*, *"month"*, *"day"* », do
1. Let _value_ be _formatOptions_.[[<_propertyKey_>]].
1. If _value_ is not *undefined*, set _needDefaults_ to *false*.
1. If _required_ is ~time~ or ~any~, then
1. For each property name _propertyKey_ of « *"dayPeriod"*, *"hour"*, *"minute"*, *"second"*, *"fractionalSecondDigits"* », do
1. Let _value_ be _formatOptions_.[[<_propertyKey_>]].
1. If _value_ is not *undefined*, set _needDefaults_ to *false*.
1. If _needDefaults_ is *true* and _defaults_ is either ~date~ or ~all~, then
1. For each property name _propertyKey_ of « *"year"*, *"month"*, *"day"* », do
1. Set _formatOptions_.[[<_propertyKey_>]] to *"numeric"*.
1. If _needDefaults_ is *true* and _defaults_ is either ~time~ or ~all~, then
1. For each property name _propertyKey_ of « *"hour"*, *"minute"*, *"second"* », do
1. Set _formatOptions_.[[<_propertyKey_>]] to *"numeric"*.
1. Let _formats_ be _resolvedLocaleData_.[[formats]].[[<_resolvedCalendar_>]].
1. If _formatMatcher_ is *"basic"*, then
1. Let _bestFormat_ be BasicFormatMatcher(_formatOptions_, _formats_).
1. Else,
1. Let _bestFormat_ be BestFitFormatMatcher(_formatOptions_, _formats_).
1. Set _dateTimeFormat_.[[DateTimeFormat]] to _bestFormat_.
1. If _bestFormat_ has a field [[hour]], then
1. Set _dateTimeFormat_.[[HourCycle]] to _hc_.
1. Return _dateTimeFormat_.
</emu-alg>
</emu-clause>
</emu-clause>
<emu-clause id="sec-properties-of-intl-datetimeformat-constructor">
<h1>Properties of the Intl.DateTimeFormat Constructor</h1>
<emu-clause id="sec-intl.datetimeformat-internal-slots" number="3">
<h1>Internal slots</h1>
<p>The value of the [[AvailableLocales]] internal slot is implementation-defined within the constraints described in <emu-xref href="#sec-internal-slots"></emu-xref>.</p>
<p>The value of the [[RelevantExtensionKeys]] internal slot is « *"ca"*, *"hc"*, *"nu"* ».</p>
<emu-note>
<a href="https://unicode.org/reports/tr35/#Key_Type_Definitions">Unicode Technical Standard #35 Part 1 Core, Section 3.6.1 Key and Type Definitions</a> describes four locale extension keys that are relevant to date and time formatting: *"ca"* for calendar, *"hc"* for hour cycle, *"nu"* for numbering system (of formatted numbers), and *"tz"* for time zone. DateTimeFormat, however, requires that the time zone is specified through the *"timeZone"* property in the options objects.
</emu-note>
<p>The value of the [[ResolutionOptionDescriptors]] internal slot is « { [[Key]]: *"ca"*, [[Property]]: *"calendar"* }, { [[Key]]: *"nu"*, [[Property]]: *"numberingSystem"* }, { [[Key]]: *"hour12"*, [[Property]]: *"hour12"*, [[Type]]: ~boolean~ }, { [[Key]]: *"hc"*, [[Property]]: *"hourCycle"*, [[Values]]: « *"h11"*, *"h12"*, *"h23"*, *"h24"* » } ».</p>
<p>The value of the [[LocaleData]] internal slot is implementation-defined within the constraints described in <emu-xref href="#sec-internal-slots"></emu-xref> and the following additional constraints, for all locale values _locale_:</p>
<ul>
<li>
[[LocaleData]].[[<_locale_>]].[[nu]] must be a List that does not include the values *"native"*, *"traditio"*, or *"finance"*.
</li>
<li>
[[LocaleData]].[[<_locale_>]].[[hc]] must be « *null*, *"h11"*, *"h12"*, *"h23"*, *"h24"* ».
</li>
<li>
[[LocaleData]].[[<_locale_>]].[[hourCycle]] must be one of the Strings *"h11"*, *"h12"*, *"h23"*, or *"h24"*.
</li>
<li>
[[LocaleData]].[[<_locale_>]].[[hourCycle12]] must be one of the Strings *"h11"* or *"h12"*.
</li>
<li>
[[LocaleData]].[[<_locale_>]].[[hourCycle24]] must be one of the Strings *"h23"* or *"h24"*.
</li>
<li>
[[LocaleData]].[[<_locale_>]] must have a [[formats]] field. The value of this [[formats]] field must be a Record with a [[<_calendar_>]] field for each calendar value _calendar_. The value of each [[<_calendar_>]] field must be a List of DateTime Format Records. Multiple Records in such a List may use the same subset of the fields as long as the corresponding values differ for at least one field. The following subsets must be available for each locale:
<ul>
<li>weekday, year, month, day, hour, minute, second, fractionalSecondDigits</li>
<li>weekday, year, month, day, hour, minute, second</li>
<li>weekday, year, month, day</li>
<li>year, month, day</li>
<li>year, month</li>
<li>month, day</li>
<li>month</li>
<li>hour, minute, second, fractionalSecondDigits</li>
<li>hour, minute, second</li>
<li>hour, minute</li>
<li>dayPeriod, hour, minute, second, fractionalSecondDigits</li>
<li>dayPeriod, hour, minute, second</li>
<li>dayPeriod, hour, minute</li>
<li>dayPeriod, hour</li>
</ul>
</li>
<li>
[[LocaleData]].[[<_locale_>]] must have a [[styles]] field. The value of this [[styles]] field must be a Record with a [[<_calendar_>]] field for each calendar value _calendar_. The value of each [[<_calendar_>]] field must be a DateTime Styles Record.
</li>
</ul>
<emu-clause id="sec-datetimeformat-format-record">
<h1>DateTime Format Records</h1>
<p>Each <dfn id="datetimeformat-format-record" variants="DateTime Format Records">DateTime Format Record</dfn> has the fields defined in <emu-xref href="#table-datetimeformat-format-record"></emu-xref>.</p>
<emu-table id="table-datetimeformat-format-record">
<emu-caption>DateTime Format Record</emu-caption>
<table class="real-table">
<thead>
<tr>
<th>Field Name</th>
<th>Value Type</th>
<th>Description</th>
</tr>
</thead>
<tr>
<td>[[weekday]]</td>
<td>[[Weekday]] values in the Values column of <emu-xref href="#table-datetimeformat-components"></emu-xref></td>
<td>Optional field. Present if [[pattern]] contains the substring *"{weekday}"*.</td>
</tr>
<tr>
<td>[[era]]</td>
<td>[[Era]] values in the Values column of <emu-xref href="#table-datetimeformat-components"></emu-xref></td>
<td>Optional field. Present if [[pattern]] contains the substring *"{era}"*.</td>
</tr>
<tr>
<td>[[year]]</td>
<td>[[Year]] values in the Values column of <emu-xref href="#table-datetimeformat-components"></emu-xref></td>
<td>Optional field. Present if [[pattern]] contains at least one of the substrings *"{year}"*, *"{yearName}"*, or *"{relatedYear}"*.</td>
</tr>
<tr>
<td>[[month]]</td>
<td>[[Month]] values in the Values column of <emu-xref href="#table-datetimeformat-components"></emu-xref></td>
<td>Optional field. Present if [[pattern]] contains the substring *"{month}"*.</td>
</tr>
<tr>
<td>[[day]]</td>
<td>[[Day]] values in the Values column of <emu-xref href="#table-datetimeformat-components"></emu-xref></td>
<td>Optional field. Present if [[pattern]] contains the substring *"{day}"*.</td>
</tr>
<tr>
<td>[[dayPeriod]]</td>
<td>[[DayPeriod]] values in the Values column of <emu-xref href="#table-datetimeformat-components"></emu-xref></td>
<td>Optional field. Present if [[pattern]] contains the substring *"{dayPeriod}"*.</td>
</tr>
<tr>
<td>[[hour]]</td>
<td>[[Hour]] values in the Values column of <emu-xref href="#table-datetimeformat-components"></emu-xref></td>
<td>Optional field. Present if [[pattern]] contains the substring *"{hour}"*.</td>
</tr>
<tr>
<td>[[minute]]</td>
<td>[[Minute]] values in the Values column of <emu-xref href="#table-datetimeformat-components"></emu-xref></td>
<td>Optional field. Present if [[pattern]] contains the substring *"{minute}"*.</td>
</tr>
<tr>
<td>[[second]]</td>
<td>[[Second]] values in the Values column of <emu-xref href="#table-datetimeformat-components"></emu-xref></td>
<td>Optional field. Present if [[pattern]] contains the substring *"{second}"*.</td>
</tr>
<tr>
<td>[[fractionalSecondDigits]]</td>
<td>[[FractionalSecondDigits]] values in the Values column of <emu-xref href="#table-datetimeformat-components"></emu-xref></td>
<td>Optional field. Present if [[pattern]] contains the substring *"{fractionalSecondDigits}"*.</td>
</tr>
<tr>
<td>[[timeZoneName]]</td>
<td>[[TimeZoneName]] values in the Values column of <emu-xref href="#table-datetimeformat-components"></emu-xref></td>
<td>Optional field. Present if [[pattern]] contains the substring *"{timeZoneName}"*.</td>
</tr>
<tr>
<td>[[pattern]]</td>
<td>a Pattern String</td>
<td><emu-not-ref>Contains</emu-not-ref> for each of the date and time format component fields of the record a substring starting with *"{"*, followed by the name of the field, followed by *"}"*. If the record has a [[year]] field, the string may contain the substrings *"{yearName}"* and *"{relatedYear}"*.</td>
</tr>
<tr>
<td>[[pattern12]]</td>
<td>a Pattern String</td>
<td>Optional field. Present if the [[hour]] field is present. In addition to the substrings of the [[pattern]] field, contains at least one of the substrings *"{ampm}"* or *"{dayPeriod}"*.</td>
</tr>
<tr>
<td>[[rangePatterns]]</td>
<td>a DateTime Range Pattern Record</td>
<td>Pattern strings in this field are similar to [[pattern]].</td>
</tr>
<tr>
<td>[[rangePatterns12]]</td>
<td>a DateTime Range Pattern Record</td>
<td>Optional field. Present if the [[hour]] field is present. Pattern strings in this field are similar to [[pattern12]].</td>
</tr>
</table>
</emu-table>
</emu-clause>
<emu-clause id="sec-datetimeformat-range-pattern-record">
<h1>DateTime Range Pattern Records</h1>
<p>Each <dfn id="datetimeformat-range-pattern-record">DateTime Range Pattern Record</dfn> has the fields defined in <emu-xref href="#table-datetimeformat-range-pattern-record"></emu-xref>.</p>
<emu-table id="table-datetimeformat-range-pattern-record">
<emu-caption>DateTime Range Pattern Record</emu-caption>
<table class="real-table">
<thead>
<tr>
<th>Field Name</th>
<th>Value Type</th>
<th>Description</th>
</tr>
</thead>
<tr>
<td>[[Default]]</td>
<td>a DateTime Range Pattern Format Record</td>
<td>It contains the default range pattern used when a more specific range pattern is not available.</td>
</tr>
<tr>
<td>[[Era]]</td>
<td>a DateTime Range Pattern Format Record</td>
<td>Optional field. Used when <em>era</em> is the largest calendar element that is different between the start and end dates.</td>
</tr>
<tr>
<td>[[Year]]</td>
<td>a DateTime Range Pattern Format Record</td>
<td>Optional field. Used when <em>year</em> is the largest calendar element that is different between the start and end dates.</td>
</tr>
<tr>
<td>[[Month]]</td>
<td>a DateTime Range Pattern Format Record</td>
<td>Optional field. Used when <em>month</em> is the largest calendar element that is different between the start and end dates.</td>
</tr>
<tr>
<td>[[Day]]</td>
<td>a DateTime Range Pattern Format Record</td>
<td>Optional field. Used when <em>day</em> is the largest calendar element that is different between the start and end dates.</td>
</tr>
<tr>
<td>[[AmPm]]</td>
<td>a DateTime Range Pattern Format Record</td>
<td>Optional field. Used when <em>ante</em> or <em>post meridiem</em> is the largest calendar element that is different between the start and end dates.</td>
</tr>
<tr>
<td>[[DayPeriod]]</td>
<td>a DateTime Range Pattern Format Record</td>
<td>Optional field. Used when <em>day period</em> is the largest calendar element that is different between the start and end dates.</td>
</tr>
<tr>
<td>[[Hour]]</td>
<td>a DateTime Range Pattern Format Record</td>
<td>Optional field. Used when <em>hour</em> is the largest calendar element that is different between the start and end dates.</td>
</tr>
<tr>
<td>[[Minute]]</td>
<td>a DateTime Range Pattern Format Record</td>
<td>Optional field. Used when <em>minute</em> is the largest calendar element that is different between the start and end dates.</td>
</tr>
<tr>
<td>[[Second]]</td>
<td>a DateTime Range Pattern Format Record</td>
<td>Optional field. Used when <em>second</em> is the largest calendar element that is different between the start and end dates.</td>
</tr>
<tr>
<td>[[FractionalSecondDigits]]</td>
<td>a DateTime Range Pattern Format Record</td>
<td>Optional field. Used when <em>fractional seconds</em> are the largest calendar element that is different between the start and end dates.</td>
</tr>
</table>
</emu-table>
</emu-clause>
<emu-clause id="sec-datetimeformat-range-pattern-format-record">
<h1>DateTime Range Pattern Format Records</h1>
<p>Each <dfn id="datetimeformat-range-pattern-format-record">DateTime Range Pattern Format Record</dfn> has the fields defined in <emu-xref href="#table-datetimeformat-range-pattern-format-record"></emu-xref>.</p>
<emu-table id="table-datetimeformat-range-pattern-format-record">
<emu-caption>DateTime Range Pattern Format Record</emu-caption>
<table class="real-table">
<thead>
<tr>
<th>Field Name</th>
<th>Value Type</th>
<th>Description</th>
</tr>
</thead>
<tr>
<td>[[weekday]]</td>
<td>[[Weekday]] values in the Values column of <emu-xref href="#table-datetimeformat-components"></emu-xref></td>
<td>Optional field. Present if a Pattern String in [[PatternParts]] contains the substring *"{weekday}"*.</td>
</tr>
<tr>
<td>[[era]]</td>
<td>[[Era]] values in the Values column of <emu-xref href="#table-datetimeformat-components"></emu-xref></td>
<td>Optional field. Present if a Pattern String in [[PatternParts]] contains the substring *"{era}"*.</td>
</tr>
<tr>
<td>[[year]]</td>
<td>[[Year]] values in the Values column of <emu-xref href="#table-datetimeformat-components"></emu-xref></td>
<td>Optional field. Present if a Pattern String in [[PatternParts]] contains at least one of the substrings *"{year}"*, *"{yearName}"*, or *"{relatedYear}"*.</td>
</tr>
<tr>
<td>[[month]]</td>
<td>[[Month]] values in the Values column of <emu-xref href="#table-datetimeformat-components"></emu-xref></td>
<td>Optional field. Present if a Pattern String in [[PatternParts]] contains the substring *"{month}"*.</td>
</tr>
<tr>
<td>[[day]]</td>
<td>[[Day]] values in the Values column of <emu-xref href="#table-datetimeformat-components"></emu-xref></td>
<td>Optional field. Present if a Pattern String in [[PatternParts]] contains the substring *"{day}"*.</td>
</tr>
<tr>
<td>[[dayPeriod]]</td>
<td>[[DayPeriod]] values in the Values column of <emu-xref href="#table-datetimeformat-components"></emu-xref></td>
<td>Optional field. Present if a Pattern String in [[PatternParts]] contains the substring *"{dayPeriod}"*.</td>
</tr>
<tr>
<td>[[hour]]</td>
<td>[[Hour]] values in the Values column of <emu-xref href="#table-datetimeformat-components"></emu-xref></td>
<td>Optional field. Present if a Pattern String in [[PatternParts]] contains the substring *"{hour}"*.</td>
</tr>
<tr>
<td>[[minute]]</td>
<td>[[Minute]] values in the Values column of <emu-xref href="#table-datetimeformat-components"></emu-xref></td>
<td>Optional field. Present if a Pattern String in [[PatternParts]] contains the substring *"{minute}"*.</td>
</tr>
<tr>
<td>[[second]]</td>
<td>[[Second]] values in the Values column of <emu-xref href="#table-datetimeformat-components"></emu-xref></td>
<td>Optional field. Present if a Pattern String in [[PatternParts]] contains the substring *"{second}"*.</td>
</tr>
<tr>
<td>[[fractionalSecondDigits]]</td>
<td>[[FractionalSecondDigits]] values in the Values column of <emu-xref href="#table-datetimeformat-components"></emu-xref></td>
<td>Optional field. Present if a Pattern String in [[PatternParts]] contains the substring *"{fractionalSecondDigits}"*.</td>
</tr>
<tr>
<td>[[timeZoneName]]</td>
<td>[[TimeZoneName]] values in the Values column of <emu-xref href="#table-datetimeformat-components"></emu-xref></td>
<td>Optional field. Present if a Pattern String in [[PatternParts]] contains the substring *"{timeZoneName}"*.</td>
</tr>
<tr>
<td>[[PatternParts]]</td>
<td>a List of DateTime Range Pattern Part Records</td>
<td>Each record represents a part of the range pattern.</td>
</tr>
</table>
</emu-table>
</emu-clause>
<emu-clause id="sec-datetimeformat-range-pattern-part-record">
<h1>DateTime Range Pattern Part Records</h1>
<p>Each <dfn id="datetimeformat-range-pattern-part-record" variants="DateTime Range Pattern Part Records">DateTime Range Pattern Part Record</dfn> has the fields defined in <emu-xref href="#table-datetimeformat-range-pattern-part-record"></emu-xref>.</p>
<emu-table id="table-datetimeformat-range-pattern-part-record">
<emu-caption>DateTime Range Pattern Part Record</emu-caption>
<table class="real-table">
<thead>
<tr>
<th>Field Name</th>
<th>Value Type</th>
<th>Description</th>
</tr>
</thead>
<tr>
<td>[[Source]]</td>
<td>*"shared"*, *"startRange"*, or *"endRange"*</td>
<td>It indicates which of the range's dates should be formatted using the value of the [[Pattern]] field.</td>
</tr>
<tr>
<td>[[Pattern]]</td>
<td>a Pattern String</td>
<td>A String of the same format as the regular date pattern String.</td>
</tr>
</table>
</emu-table>
</emu-clause>
<emu-clause id="sec-datetimeformat-styles-record">
<h1>DateTime Styles Records</h1>
<p>Each <dfn id="datetimeformat-styles-record">DateTime Styles Record</dfn> has the fields defined in <emu-xref href="#table-datetimeformat-styles-record"></emu-xref>.</p>
<emu-table id="table-datetimeformat-styles-record">
<emu-caption>DateTime Styles Record</emu-caption>
<table class="real-table">
<thead>
<tr>
<th>Field Name</th>
<th>Value Type</th>
</tr>
</thead>
<tr>
<td>[[Date]]</td>
<td>a DateTime Style Record</td>
</tr>
<tr>
<td>[[Time]]</td>
<td>a DateTime Style Record</td>
</tr>
<tr>
<td>[[Connector]]</td>
<td>a DateTime Connector Record</td>
</tr>
<tr>
<td>[[DateTimeRangeFormat]]</td>
<td>a DateTime Date Range Record</td>
</tr>
</table>
</emu-table>
</emu-clause>
<emu-clause id="sec-datetimeformat-style-record">
<h1>DateTime Style Records</h1>
<p>Each <dfn id="datetimeformat-style-record">DateTime Style Record</dfn> has the fields defined in <emu-xref href="#table-datetimeformat-style-record"></emu-xref>.</p>
<emu-table id="table-datetimeformat-style-record">
<emu-caption>DateTime Style Record</emu-caption>
<table class="real-table">
<thead>
<tr>
<th>Field Name</th>
<th>Value Type</th>
<th>Description</th>
</tr>
</thead>
<tr>
<td>[[full]]</td>
<td>a DateTime Format Record</td>
<td>Format record for the *"full"* style.</td>
</tr>
<tr>
<td>[[long]]</td>
<td>a DateTime Format Record</td>
<td>Format record for the *"long"* style.</td>
</tr>
<tr>
<td>[[medium]]</td>
<td>a DateTime Format Record</td>
<td>Format record for the *"medium"* style.</td>
</tr>
<tr>
<td>[[short]]</td>
<td>a DateTime Format Record</td>
<td>Format record for the *"short"* style.</td>
</tr>
</table>
</emu-table>
</emu-clause>
<emu-clause id="sec-datetimeformat-connector-record">
<h1>DateTime Connector Records</h1>
<p>Each <dfn id="datetimeformat-connector-record">DateTime Connector Record</dfn> has the fields defined in <emu-xref href="#table-datetimeformat-connector-record"></emu-xref>. All connector pattern strings must contain the strings *"{0}"* and *"{1}"*.</p>
<emu-table id="table-datetimeformat-connector-record">
<emu-caption>DateTime Connector Record</emu-caption>
<table class="real-table">
<thead>
<tr>
<th>Field Name</th>
<th>Value Type</th>
<th>Description</th>
</tr>
</thead>
<tr>
<td>[[full]]</td>
<td>a Pattern String</td>
<td>Connector pattern when the date style is *"full"*.</td>
</tr>
<tr>
<td>[[long]]</td>
<td>a Pattern String</td>
<td>Connector pattern when the date style is *"long"*.</td>
</tr>
<tr>
<td>[[medium]]</td>
<td>a Pattern String</td>
<td>Connector pattern when the date style is *"medium"*.</td>
</tr>
<tr>
<td>[[short]]</td>
<td>a Pattern String</td>
<td>Connector pattern when the date style is *"short"*.</td>
</tr>
</table>
</emu-table>
</emu-clause>
<emu-clause id="sec-datetimeformat-date-range-record">
<h1>DateTime Date Range Records</h1>
<p>Each <dfn id="datetimeformat-date-range-record">DateTime Date Range Record</dfn> has the fields defined in <emu-xref href="#table-datetimeformat-date-range-record"></emu-xref>.</p>
<emu-table id="table-datetimeformat-date-range-record">
<emu-caption>DateTime Date Range Record</emu-caption>
<table class="real-table">
<thead>
<tr>
<th>Field Name</th>
<th>Value Type</th>
<th>Description</th>
</tr>
</thead>
<tr>
<td>[[full]]</td>
<td>a DateTime Time Range Record</td>
<td>Used when date style is *"full"*.</td>
</tr>
<tr>
<td>[[long]]</td>
<td>a DateTime Time Range Record</td>
<td>Used when date style is *"long"*.</td>
</tr>
<tr>
<td>[[medium]]</td>
<td>a DateTime Time Range Record</td>
<td>Used when date style is *"medium"*.</td>
</tr>
<tr>
<td>[[short]]</td>
<td>a DateTime Time Range Record</td>
<td>Used when date style is *"short"*.</td>
</tr>
</table>
</emu-table>
</emu-clause>
<emu-clause id="sec-datetimeformat-time-range-record">
<h1>DateTime Time Range Records</h1>
<p>Each <dfn id="datetimeformat-time-range-record">DateTime Time Range Record</dfn> has the fields defined in <emu-xref href="#table-datetimeformat-time-range-record"></emu-xref>.</p>
<emu-table id="table-datetimeformat-time-range-record">
<emu-caption>DateTime Time Range Record</emu-caption>
<table class="real-table">
<thead>
<tr>
<th>Field Name</th>
<th>Value Type</th>
<th>Description</th>
</tr>
</thead>
<tr>
<td>[[full]]</td>
<td>a DateTime Style Range Record</td>
<td>Used when time style is *"full"*.</td>
</tr>
<tr>
<td>[[long]]</td>
<td>a DateTime Style Range Record</td>
<td>Used when time style is *"long"*.</td>
</tr>
<tr>
<td>[[medium]]</td>
<td>a DateTime Style Range Record</td>
<td>Used when time style is *"medium"*.</td>
</tr>
<tr>
<td>[[short]]</td>
<td>a DateTime Style Range Record</td>
<td>Used when time style is *"short"*.</td>
</tr>
</table>
</emu-table>
</emu-clause>
<emu-clause id="sec-datetimeformat-style-range-record">
<h1>DateTime Style Range Records</h1>
<p>Each <dfn id="datetimeformat-style-range-record">DateTime Style Range Record</dfn> has the fields defined in <emu-xref href="#table-datetimeformat-style-range-record"></emu-xref>.</p>
<emu-table id="table-datetimeformat-style-range-record">
<emu-caption>DateTime Style Range Record</emu-caption>
<table class="real-table">
<thead>
<tr>
<th>Field Name</th>
<th>Value Type</th>
<th>Description</th>
</tr>
</thead>
<tr>
<td>[[rangePatterns]]</td>
<td>a DateTime Range Pattern Record</td>
<td>Range patterns to combine date and time styles.</td>
</tr>
<tr>
<td>[[rangePatterns12]]</td>
<td>a DateTime Range Pattern Record</td>
<td>Optional Field. Range patterns to combine date and time styles for 12-hour formats.</td>
</tr>
</table>
</emu-table>
</emu-clause>
<emu-note>
For example, an implementation might include the following Record as part of its English locale data:
<ul>
<li>[[hour]]: *"numeric"*</li>
<li>[[minute]]: *"numeric"*</li>
<li>[[pattern]]: *"{hour}:{minute}"*</li>
<li>[[pattern12]]: *"{hour}:{minute} {ampm}"*</li>
<li>[[rangePatterns]]:
<ul>
<li>[[Hour]]:
<ul>
<li>[[hour]]: *"numeric"*</li>
<li>[[minute]]: *"numeric"*</li>
<li>[[PatternParts]]:
<ul>
<li>{[[Source]]: *"startRange"*, [[Pattern]]: *"{hour}:{minute}"*}</li>
<li>{[[Source]]: *"shared"*, [[Pattern]]: *" – "*}</li>
<li>{[[Source]]: *"endRange"*, [[Pattern]]: *"{hour}:{minute}"*}</li>
</ul>
</li>
</ul>
</li>
<li>[[Minute]]:
<ul>
<li>[[hour]]: *"numeric"*</li>
<li>[[minute]]: *"numeric"*</li>
<li>[[PatternParts]]:
<ul>
<li>{[[Source]]: *"startRange"*, [[Pattern]]: *"{hour}:{minute}"*}</li>
<li>{[[Source]]: *"shared"*, [[Pattern]]: *" – "*}</li>
<li>{[[Source]]: *"endRange"*, [[Pattern]]: *"{hour}:{minute}"*}</li>
</ul>
</li>
</ul>
</li>
<li>[[Default]]:
<ul>
<li>[[year]]: *"2-digit"*</li>
<li>[[month]]: *"numeric"*</li>
<li>[[day]]: *"numeric"*</li>
<li>[[hour]]: *"numeric"*</li>
<li>[[minute]]: *"numeric"*</li>
<li>[[PatternParts]]:
<ul>
<li>{[[Source]]: *"startRange"*, [[Pattern]]: *"{day}/{month}/{year}, {hour}:{minute}"*}</li>
<li>{[[Source]]: *"shared"*, [[Pattern]]: *" – "*}</li>
<li>{[[Source]]: *"endRange"*, [[Pattern]]: *"{day}/{month}/{year}, {hour}:{minute}"*}</li>
</ul>
</li>
</ul>
</li>
</ul>
</li>
<li>[[rangePatterns12]]:
<ul>
<li>[[Hour]]:
<ul>
<li>[[hour]]: *"numeric"*</li>
<li>[[minute]]: *"numeric"*</li>
<li>[[PatternParts]]:
<ul>
<li>{[[Source]]: *"startRange"*, [[Pattern]]: *"{hour}:{minute}"*}</li>
<li>{[[Source]]: *"shared"*, [[Pattern]]: *" – "*}</li>
<li>{[[Source]]: *"endRange"*, [[Pattern]]: *"{hour}:{minute}"*}</li>
<li>{[[Source]]: *"shared"*, [[Pattern]]: *" {ampm}"*}</li>
</ul>
</li>
</ul>
</li>
<li>[[Minute]]:
<ul>
<li>[[hour]]: *"numeric"*</li>
<li>[[minute]]: *"numeric"*</li>
<li>[[PatternParts]]:
<ul>
<li>{[[Source]]: *"startRange"*, [[Pattern]]: *"{hour}:{minute}"*}</li>
<li>{[[Source]]: *"shared"*, [[Pattern]]: *" – "*}</li>
<li>{[[Source]]: *"endRange"*, [[Pattern]]: *"{hour}:{minute}"*}</li>
<li>{[[Source]]: *"shared"*, [[Pattern]]: *" {ampm}"*}</li>
</ul>
</li>
</ul>
</li>
<li>[[Default]]:
<ul>
<li>[[year]]: *"2-digit"*</li>
<li>[[month]]: *"numeric"*</li>
<li>[[day]]: *"numeric"*</li>
<li>[[hour]]: *"numeric"*</li>
<li>[[minute]]: *"numeric"*</li>
<li>[[PatternParts]]:
<ul>
<li>{[[Source]]: *"startRange"*, [[Pattern]]: *"{day}/{month}/{year}, {hour}:{minute} {ampm}"*}</li>
<li>{[[Source]]: *"shared"*, [[Pattern]]: *" – "*}</li>
<li>{[[Source]]: *"endRange"*, [[Pattern]]: *"{day}/{month}/{year}, {hour}:{minute} {ampm}"*}</li>
</ul>
</li>
</ul>
</li>
</ul>
</li>
</ul>
</emu-note>
<emu-note>
It is recommended that implementations use the locale data provided by the Common Locale Data Repository (available at <a href="https://cldr.unicode.org/">https://cldr.unicode.org/</a>).
</emu-note>
</emu-clause>
</emu-clause>
<emu-clause id="sec-properties-of-intl-datetimeformat-prototype-object">
<h1>Properties of the Intl.DateTimeFormat Prototype Object</h1>
<emu-clause id="sec-intl.datetimeformat.prototype.resolvedoptions" number="2">
<h1>Intl.DateTimeFormat.prototype.resolvedOptions ( )</h1>
<p>This function provides access to the locale and options computed during initialization of the object.</p>
<emu-alg>
1. Let _dtf_ be the *this* value.
1. If the implementation supports the normative optional constructor mode of <emu-xref href="#legacy-constructor"></emu-xref>, then
1. Set _dtf_ to ? UnwrapDateTimeFormat(_dtf_).
1. Perform ? RequireInternalSlot(_dtf_, [[InitializedDateTimeFormat]]).
1. Let _options_ be OrdinaryObjectCreate(%Object.prototype%).
1. For each row of <emu-xref href="#table-datetimeformat-resolvedoptions-properties"></emu-xref>, except the header row, in table order, do
1. Let _propertyKey_ be the Property value of the current row.
1. If there is an Internal Slot value in the current row, then
1. Let _value_ be the value of _dtf_'s internal slot whose name is the Internal Slot value of the current row.
1. Else,
1. Let _format_ be _dtf_.[[DateTimeFormat]].
1. If _format_ has a field [[<_propertyKey_>]] and _dtf_.[[DateStyle]] is *undefined* and _dtf_.[[TimeStyle]] is *undefined*, then
1. Let _value_ be _format_.[[<_propertyKey_>]].
1. Else,
1. Let _value_ be *undefined*.
1. If _value_ is not *undefined*, then
1. If there is a Conversion value in the current row, then
1. Let _conversion_ be the Conversion value of the current row.
1. If _conversion_ is ~hour12~, then
1. If _value_ is *"h11"* or *"h12"*, set _value_ to *true*. Otherwise, set _value_ to *false*.
1. Else,
1. Assert: _conversion_ is ~number~.
1. Set _value_ to 𝔽(_value_).
1. Perform ! CreateDataPropertyOrThrow(_options_, _propertyKey_, _value_).
1. Return _options_.
</emu-alg>
<emu-table id="table-datetimeformat-resolvedoptions-properties">
<emu-caption>Resolved Options of DateTimeFormat Instances</emu-caption>
<table class="real-table">
<thead>
<tr>
<th>Internal Slot</th>
<th>Property</th>
<th>Conversion</th>
</tr>
</thead>
<tr>
<td>[[Locale]]</td>
<td>*"locale"*</td>
<td></td>
</tr>
<tr>
<td>[[Calendar]]</td>
<td>*"calendar"*</td>
<td></td>
</tr>
<tr>
<td>[[NumberingSystem]]</td>
<td>*"numberingSystem"*</td>
<td></td>
</tr>
<tr>
<td>[[TimeZone]]</td>
<td>*"timeZone"*</td>
<td></td>
</tr>
<tr>
<td>[[HourCycle]]</td>
<td>*"hourCycle"*</td>
<td></td>
</tr>
<tr>
<td>[[HourCycle]]</td>
<td>*"hour12"*</td>
<td>~hour12~</td>
</tr>
<tr>
<td></td>
<td>*"weekday"*</td>
<td></td>
</tr>
<tr>
<td></td>
<td>*"era"*</td>
<td></td>
</tr>
<tr>
<td></td>
<td>*"year"*</td>
<td></td>
</tr>
<tr>
<td></td>
<td>*"month"*</td>
<td></td>
</tr>
<tr>
<td></td>
<td>*"day"*</td>
<td></td>
</tr>
<tr>
<td></td>
<td>*"dayPeriod"*</td>
<td></td>
</tr>
<tr>
<td></td>
<td>*"hour"*</td>
<td></td>
</tr>
<tr>
<td></td>
<td>*"minute"*</td>
<td></td>
</tr>
<tr>
<td></td>
<td>*"second"*</td>
<td></td>
</tr>
<tr>
<td></td>
<td>*"fractionalSecondDigits"*</td>
<td>~number~</td>
</tr>
<tr>
<td></td>
<td>*"timeZoneName"*</td>
<td></td>
</tr>
<tr>
<td>[[DateStyle]]</td>
<td>*"dateStyle"*</td>
<td></td>
</tr>
<tr>
<td>[[TimeStyle]]</td>
<td>*"timeStyle"*</td>
<td></td>
</tr>
</table>
</emu-table>
<p>For web compatibility reasons, if the property *"hourCycle"* is set, the *"hour12"* property should be set to *true* when *"hourCycle"* is *"h11"* or *"h12"*, or to *false* when *"hourCycle"* is *"h23"* or *"h24"*.</p>
<emu-note>
In this version of the API, the *"timeZone"* property will be the identifier of the host environment's time zone if no *"timeZone"* property was provided in the options object provided to the Intl.DateTimeFormat constructor. The first edition left the *"timeZone"* property *undefined* in this case.
</emu-note>
<emu-note>
For compatibility with versions prior to the fifth edition, the *"hour12"* property is set in addition to the *"hourCycle"* property.
</emu-note>
</emu-clause>
</emu-clause>
<emu-clause id="sec-properties-of-intl-datetimeformat-instances">
<h1>Properties of Intl.DateTimeFormat Instances</h1>
<p>Intl.DateTimeFormat instances are ordinary objects that inherit properties from %Intl.DateTimeFormat.prototype%.</p>
<p>Intl.DateTimeFormat instances have an [[InitializedDateTimeFormat]] internal slot.</p>
<p>Intl.DateTimeFormat instances also have several internal slots that are computed by <emu-xref href="#sec-intl-datetimeformat-constructor" title></emu-xref>:</p>
<ul>
<li>[[Locale]] is a String representing the language tag of the locale whose localization is used for formatting.</li>
<li>[[Calendar]] is a String representing the <a href="https://unicode.org/reports/tr35/#UnicodeCalendarIdentifier">Unicode Calendar Identifier</a> used for formatting.</li>
<li>[[NumberingSystem]] is a String representing the <a href="https://unicode.org/reports/tr35/#UnicodeNumberSystemIdentifier">Unicode Number System Identifier</a> used for formatting.</li>
<li>[[TimeZone]] is a String used for formatting that is either an available named time zone identifier or an offset time zone identifier.</li>
<li>[[HourCycle]] is a String indicating whether the 12-hour format (*"h11"*, *"h12"*) or the 24-hour format (*"h23"*, *"h24"*) should be used. *"h11"* and *"h23"* start with hour 0 and go up to 11 and 23 respectively. *"h12"* and *"h24"* start with hour 1 and go up to 12 and 24. [[HourCycle]] is only used when [[DateTimeFormat]] has an [[hour]] field.</li>
<li>[[DateStyle]], [[TimeStyle]] are each either *undefined*, *"full"*, *"long"*, *"medium"*, or *"short"*.</li>
<li>[[DateTimeFormat]] is a DateTime Format Record.</li>
</ul>
<p>Finally, Intl.DateTimeFormat instances have a [[BoundFormat]] internal slot that caches the function returned by the format accessor (<emu-xref href="#sec-intl.datetimeformat.prototype.format"></emu-xref>).</p>
</emu-clause>
<emu-clause id="sec-datetimeformat-abstracts">
<h1>Abstract Operations for DateTimeFormat Objects</h1>
<p>Several DateTimeFormat algorithms use values from the following table, which provides internal slots, property names and allowable values for the components of date and time formats:</p>
<emu-table id="table-datetimeformat-components">
<emu-caption>Components of date and time formats</emu-caption>
<table class="real-table">
<thead>
<tr>
<th>Field Name</th>
<th>Property</th>
<th>Values</th>
</tr>
</thead>
<tr>
<td>[[Weekday]]</td>
<td>*"weekday"*</td>
<td>*"narrow"*, *"short"*, *"long"*</td>
</tr>
<tr>
<td>[[Era]]</td>
<td>*"era"*</td>
<td>*"narrow"*, *"short"*, *"long"*</td>
</tr>
<tr>
<td>[[Year]]</td>
<td>*"year"*</td>
<td>*"2-digit"*, *"numeric"*</td>
</tr>
<tr>
<td>[[Month]]</td>
<td>*"month"*</td>
<td>*"2-digit"*, *"numeric"*, *"narrow"*, *"short"*, *"long"*</td>
</tr>
<tr>