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hijri-core

@spezutil/hijri-core is the zero-dependency calendar engine behind the picker. Use it directly for conversions and formatting.

import { createCalendar, formatHijri, parseHijri } from "@spezutil/hijri-core";

const cal = createCalendar();
const h = cal.gregorianToHijri(new Date(Date.UTC(2024, 2, 15)));
formatHijri(h, "D MMMM YYYY"); // e.g. "5 Ramadan al-Moazzam 1445"
cal.hijriToGregorian(h); // back to a Date

The Misri / Fatimid algorithm​

The Dawoodi Bohra calendar is a fixed tabular calendar, fully determined by a leap-year cycle and an epoch:

  • 30-year cycle with leap years at positions 2, 5, 8, 10, 13, 16, 19, 21, 24, 27, 29.
  • Odd months are 30 days, even months 29; in a leap year the 12th month (Zilhaj) has 30 days.
  • Epoch: 1 Muharram, year 1 corresponds to 15 July 622 CE, calibrated against authoritative anchor dates (Lokhandwala Misri conversion tables).

Correction layer​

createCalendar({ corrections }) accepts overrides keyed by Gregorian ISO date, layered on top of the tabular result for any date that must match an authoritative source exactly:

const cal = createCalendar({
  corrections: { "2024-01-15": { year: 1445, month: 7, day: 3 } },
});

Formatting tokens​

formatHijri supports YYYY, MMMM (month name), MM, M, DD, D. parseHijri parses the numeric tokens (YYYY, MM, DD).