[justingrantjg]

There are 5 different `islamic-*` calendars (and a `persian` calendar too) supported in JS today: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Refe...

There's no geographic adjustment but at least there is some choice for users about which Islamic calendar variation should be used. For example, "islamic-rgsa" in JS is the Hijri calendar, Saudi Arabia sighting.

Temporal has built-in support for non-Gregorian calendars, including parsing, arithmetic, etc. so you can do things like this:

Temporal.PlainDate.from("2025-01-30").withCalendar('islamic-rgsa').month // => 8

Temporal.PlainDate.from("2025-01-30[u-ca=islamic-rgsa]').month // => 8

function chineseNewYears() { const dt = Temporal.Now.plainDateISO().withCalendar('chinese'); const current = Temporal.PlainDate.from({year: dt.year, month: 1, day: 1, calendar: 'chinese'}) const next = current.add({years: 1}) return { current, next } } `The next Chinese New Year is ${chineseNewYears().next.withCalendar('gregory').toLocaleString('en-UK')}` // => 'The next Chinese New Year is 17/02/2026'

More info about how calendars are used in Temporal is here: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Refe...