Festivals

const r = getDailyPanchang(date, loc, { timezone: 330 })!;

r.festivals.forEach(f => {
  // key:  stable, language-independent id — 'diwali', 'makar_sankranti', …
  // type: major | minor | ekadashi | smarta_ekadashi | vaishnava_ekadashi
  //     | pradosha | sankranti | eclipse
  console.log(f.key, f.name, f.type, f.deferralDate);
});

// `name` is localized, so match on `key` — never on `name`.
const hasDiwali = r.festivals.some(f => f.key === 'diwali');

// All regional variants (default):
getDailyPanchang(jan14, chennai, { timezone: 330 })!.festivals.map(f => f.name);
// → ["Sankranti","Makar Sankranti","Pongal","Uttarayan","Magh Bihu","Ayyappa Makara Jyothi"]

// Tamil Nadu only:
getDailyPanchang(jan14, chennai, { timezone: 330, region: 'tamil-nadu' })!
  .festivals.map(f => f.name);
// → ["Sankranti","Makar Sankranti","Pongal"]

// Lohri fires on the Hindu day BEFORE Makara transit, in Punjab/Haryana/Himachal scope:
getDailyPanchang(jan13, amritsar, { timezone: 330, region: 'punjab' })!
  .festivals.some(f => f.name === 'Lohri'); // true

import { buildFestivalsTable } from 'panchang-ts';            // uses the engine
import {
  readFestivalsForYear,
  readFestivalsForDate,
  readFestivalsYearRange,
} from 'panchang-ts/festivals';                                // engine-free

// Build once — at your build time, or on first launch in the background.
const table = buildFestivalsTable({
  location: { latitude: 25.3176, longitude: 82.9739 },   // Varanasi
  timezoneOffsetMinutes: 330,    // IST; -300 = US Eastern, 0 = UK
  startYear: 2024,
  endYear: 2031,
  languages: ['en', 'hi'],       // drop 'hi' to halve the size
  referenceLocation: 'Varanasi',
});
// …persist `table` as JSON (disk / MMKV / your bundler's asset pipeline).

// Later reads are instant lookups — no engine, no ephemeris.
readFestivalsYearRange(table);                    // { start: 2024, end: 2031 }
readFestivalsForYear(table, 2026)!.length;        // ~150 festival days
const diwali = readFestivalsForYear(table, 2026)!
  .find(d => d.festivals.some(f => f.name === 'Diwali'))!.date;
readFestivalsForDate(table, diwali);              // [Narak Chaturdashi, Diwali]
readFestivalsForDate(table, diwali, 'hi');        // [नरक चतुर्दशी, दिवाली]