New getter (and setter?) for dow

[CasperWSchmidt]

With reference to https://github.com/dangrossman/bootstrap-daterangepicker/issues/401 I would say that moment.js needs a way to get (and possibly also set) dow/first day of week. I don't know is moment.weekday(0) can somehow be used for this, but a moment.DOW(), FirstDayOfWeek() or similar seems to be missing (and quite simple to implement)

[ichernev]

You can set the first day of week by switching to an appropriate locale or defining a new one.

For now changing the start-of-week outside / orthogonal to locale is not implemented.

[CasperWSchmidt]

@ichernev I know how to set the start-of-week by using a locale (which is exactly what I'm doing), but to accommodate plugins/libs that build on moment.js a getter is needed to avoid them hooking up on internal moment.js properties (ie. _lang._week.dow). Please see the issue I linked for details on why such a getter would be a good idea.

[ichernev]

Ah, sorry. Now I got you. Yeah, adding a setter for the language should be an easy task.

Locale.prototype.firstDayOfWeek(); // 0
Locale.prototype.firstWeekOfYearOfYear(); // 6

[timrwood]

It's also possible with public apis.

moment().locale('en').weekday(0).day(); // 0
moment().locale('ar').weekday(0).day(); // 6

[CasperWSchmidt]

So to dynamically get the DOW one will have to use moment().locale(moment().lang()).weekday(0).day() or something like that? That seems a bit too long/difficult IMHO.

[nikoskalogridis]

in the Eonasdan/bootstrap-datetimepicker we used to rely on ._week.dow as well which was a bit of an issue as we were peeking on a 'protected' attribute. The way we choose to go forward was to replace that with moment().startOf('w').day()

[icambron]

@CasperWSchmidt no, you would just skip the locale stuff altogether:

moment().weekday(0).day();

You only need to specify the locale if you want the start of weekday in some arbitrary locale.

Also, you can cut out one step from your original solution by using the public localeData() call:

moment.localeData()._week.dow;

//or

moment.localeData('fr')._week.dow;

That's not great either, so yeah, I support adding a getter to the Locale prototype, which would result in:

moment.localeData().firstDateOfWeek();

//or

moment.localeData('fr').firstDayOfWeek();

//or even on an instance:

moment().localeData().firstDayOfWeek();