plainYearMonth

const plainYearMonth: RegExp = /^(?:\d{4}|\+\d{6}|-(?!0{6})\d{6})-(?:0[1-9]|1[0-2])$/;

RegExp matching an ISO 8601 year-month in the extended form: YYYY-MM or ±YYYYYY-MM.

Examples

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

plainYearMonth.test("2026-10") // true
plainYearMonth.test("+275760-09") // true
plainYearMonth.test("+999999-12") // true (shape only; outside Temporal's range)
plainYearMonth.test("202610") // false (basic format)
plainYearMonth.test("2026-13") // false (month 13)
plainYearMonth.test("2026-10-01") // false (a full date)

Source

regex/year-month.ts