First day of the week -- Intl.getCalendarInfo()

[gpbl]

It seems like there's no way with the current specifications to know the first day of the week for a given locale.

I understand ISO 8601 does consider Monday as the first working day: maybe this is the reason. However there are some locales (AFAIK Canada, U.S. and Mexico) where Sunday should be shown as first day of the week - eg in calendars or date pickers. Is there any plan to make available this information?

[rxaviers]

The first day of the week drastically varies between Saturday, Sunday, or Monday (or even Friday) between different locales: https://github.com/unicode-cldr/cldr-core/blob/master/supplemental/weekData.json#L61. So, it's definitively wrong to assume it's always Monday.

On jQuery UI datepicker, this information is pulled from CLDR https://github.com/jquery/jquery-ui/blob/datepicker-globalize-1.x/ui/calendar.js#L187 (which in turn, uses https://github.com/rxaviers/cldrjs/blob/master/src/supplemental/main.js#L22-L25).

Having said that, I agree it's useful having this information available for implementations like datepicker. Although, I leave it open for discussion on how this information should be exposed.

[caridy]

Obviously we don't use such information today as part of the current spec, but we have been talking about exposing more low-level abstract operations and data in issue #5, maybe exposing low level data like this falls into the same bucket.

[zbraniecki]

It would be also helpful for all calendar UIs.

[caridy]

Ok, let's find a champion for this feature, I can help with the spec.

[zbraniecki]

Do we also want weekendStarts and weekendEnds here? Seems relevant.

[caridy]

@zbraniecki can you double check that we have that information in CLDR?

[rxaviers]

Yes, CLDR has this information. Another related information that might be useful on calendars implementations is the first day of the year.

[zbraniecki]

It has it here: http://www.unicode.org/repos/cldr/trunk/common/supplemental/supplementalData.xml

[caridy]

great!

[srl295]

Note tr35 specifically:

The day indicated by firstDay is the one that should be shown as the first day of the week in a calendar view. This is not necessarily the same as the first day after the weekend (or the first work day of the week), which should be determined from the weekend information. Currently, day-of-week numbering is based on firstDay (that is, day 1 is the day specified by firstDay), but in the future we may add a way to specify this separately.

What is meant by the weekend varies from country to country. It is typically when most non-retail businesses are closed. The time should not be specified unless it is a well-recognized part of the day. The weekendStart day defaults to "sat", and weekendEnd day defaults to "sun". For more information, see Dates and Date Ranges.

So two concepts: "the weekend" and "first day of week for calendar display".

[zbraniecki]

Now, the question is where do we want to display it. One idea is to use Intl.Locale API (#46) to get a list of information about the given locale. Things like:

• firstDayOfTheWeek
• weekendStarts, weekendEnds
• direction (ltr/rtl)
• calendar type

and maybe one day:

• ordered list of currencies
• ordered list of timezones
• ordered list of scripts

This stuff we could get from supplemental CLDR data, and might help pushing those options to the top of selection lists for a selected locale.

But the basics are already available and I was already planning providing getDirection(locale) function. Maybe instead it should be Intl.Locale.getLocaleInfo(locale) ?

[realityking]

I like the idea of getLocaleInfo, easy to expand later without adding dozens of methods.