calendarDate

const calendarDate: RegExp = /^(\d{4}|\+\d{6}|-(?!0{6})\d{6})-(0[1-9]|1[0-2])-(0[1-9]|[12]\d|3[01])\[(!)?u-ca=([A-Za-z0-9]+(?:-[A-Za-z0-9]+)*)\]$/;

RegExp matching a calendar-annotated PlainDate string in the RFC 9557 form Temporal writes and reads: the ISO 8601 date, then one [u-ca=<id>] calendar annotation. The digits are always ISO; the annotation only names the calendar the date is presented in (RFC 9557 §3.3). This is exactly Temporal.PlainDate#toString() for a non-ISO calendar.

Examples

import { calendarDate } from "@northguild/gmt";

calendarDate.test("2024-10-03[u-ca=hebrew]") // true
calendarDate.test("+275760-09-13[u-ca=hebrew]") // true
calendarDate.test("2024-10-03[!u-ca=japanese]") // true (critical flag)
calendarDate.test("0006-10-03[u-ca=japanese;era=reiwa]") // false (not RFC 9557)
calendarDate.test("279517-10-11[u-ca=hebrew]") // false (a six-digit year needs a sign)
calendarDate.test("2024-03-15") // false (no calendar annotation)

Source

regex/calendar-date.ts