demo · v144

Calendar Explorer

Temporal makes non-Gregorian calendars a first-class concept — not a string you pass to Intl.DateTimeFormat. Render one ISO date in eight calendar systems and see month indexes, leap structure, and era names diverge.

Temporal: checking…

calendaryearmonthdayeramonthCodetoString()

the API

const iso = Temporal.PlainDate.from("2026-05-30");

// project the same instant into another calendar
const hebrew  = iso.withCalendar("hebrew");
const islamic = iso.withCalendar("islamic-umalqura");
const persian = iso.withCalendar("persian");

hebrew.year;        // 5786
hebrew.monthCode;   // "M09"
hebrew.toString();  // 2026-05-30[u-ca=hebrew]

// month codes are stable across calendars and handle leap months
// ("M05L" = leap Adar in the Hebrew calendar)

see also