Intl.DateTimeFormat

[TorsteinHonsi]

Implemented locale-aware datetime formats through the Intl.DateTimeFormat browser API. All default time formats are now respecting the browser locale.

To do

• Decide where to set the locale option. Probably best as chart.locale.
• Align the locale option with Intl. In type definitions, allow arrays and instances of Intl.Locale.
• Add object defaults for all other time definitions except those of a non-locale nature like %Y-%m-%d.
• Implement caching for DateTimeFormat instances.
• Handle capitalization for standalone formats like x-axis labels and tooltip headers. Could be a custom option on the extended Intl.DateTimeFormatOptions. Or maybe a templating helper. Axis and current-date done via the simple call to Time.dateFormat. But tooltips need to be handled another way through a sentenceCase custom property, and abstraction of Intl.DateTimeFormat.
• Handle extended or concatenated formats lik "Week from Monday, ..." and the to formats. Consider a custom prefix option on Intl.DateTimeFormatOptions. Which means we would need our own Time.DateTimeFormatOptions that extends Intl.
• Consider template keys for the most common ones.
• Consider localized defaults for lang.months, lang.weekdays etc. Will fix demos like gantt/current-date-indicator/demo.
• Separate error handling between bad timezone and bad config, see comment.

[highsoft-bot]

File size comparison

Sizes for compiled+gzipped (bold) and compiled files.

	master	candidate	difference
highcharts.js	95.8 kB 270.2 kB	96.0 kB 271.2 kB	253 B 1059 B
highstock.js	128.6 kB 371.9 kB	128.9 kB 373.0 kB	296 B 1186 B
highmaps.js	121.6 kB 349.5 kB	121.9 kB 350.5 kB	250 B 1059 B
highcharts-gantt.js	133.8 kB 385.8 kB	134.1 kB 387.0 kB	309 B 1257 B
dashboards/dashboards.js	43.1 kB 148.4 kB	43.2 kB 149.0 kB	147 B 693 B
datagrid/datagrid.js	24.7 kB 76.8 kB	24.8 kB 77.5 kB	153 B 693 B

[highsoft-bot]

Visual test results - Differences found

Found 113 diffing sample(s). Please review the differences.

---

Samples changed

Change type	Sample
Modified	samples/highcharts/studies/intl-datetimeformat/demo.js
Modified	samples/highcharts/studies/intl-datetimeformat/demo.js
Modified	samples/highcharts/studies/intl-datetimeformat/demo.js
Modified	samples/highcharts/studies/intl-datetimeformat/demo.js
Modified	samples/highcharts/studies/intl-datetimeformat/demo.js

[highsoft-bot]

Benchmark report - Stock

benchmarks/Stock/Stock-DataGrouping.bench.ts

Sample size	This PR avg (ms)	master avg (ms)	Diff	Percent diff
1000000	1033.84	1031.46	2.38	0%

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Sample size	This PR avg (ms)	master avg (ms)	Diff	Percent diff
1000	244.96	246.22	-1.26	-1%
10000	259.07	256.44	2.63	1%
100000	393.44	383.38	10.05	3%
1000000	1033.84	1031.46	2.38	0%

benchmarks/Stock/Stock-Base.bench.ts

Sample size	This PR avg (ms)	master avg (ms)	Diff	Percent diff
1000000	6294.19	6209.5	84.68	1%

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Sample size	This PR avg (ms)	master avg (ms)	Diff	Percent diff
1000	263.11	250.39	12.72	5%
10000	348.57	343.37	5.21	2%
100000	905.77	906.26	-0.49	0%
1000000	6294.19	6209.5	84.68	1%

benchmarks/Stock/Stock-DataGrouping-Ordinal.bench.ts

Sample size	This PR avg (ms)	master avg (ms)	Diff	Percent diff
1000000	1404.53	1404.37	0.16	0%

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Sample size	This PR avg (ms)	master avg (ms)	Diff	Percent diff
1000	265.77	260.71	5.06	2%
10000	278.86	279.14	-0.28	0%
100000	494.01	495.44	-1.43	0%
1000000	1404.53	1404.37	0.16	0%

benchmarks/Stock/Stock-Ordinal.bench.ts

Sample size	This PR avg (ms)	master avg (ms)	Diff	Percent diff
1000000	1406.64	1402.03	4.61	0%

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Sample size	This PR avg (ms)	master avg (ms)	Diff	Percent diff
1000	258.01	259.4	-1.4	-1%
10000	279.78	276.96	2.82	1%
100000	490.45	493.58	-3.12	-1%
1000000	1406.64	1402.03	4.61	0%