Installation

All PrayCalc packages are published to npm, written in TypeScript, and ship both ESM and CommonJS builds. Install only what you need.

Requirements

Node.js 20 or later
TypeScript 5.0 or later (optional but recommended)
pnpm, npm, or yarn

pray-calc

The main prayer times engine. Supports all 14 standard calculation methods plus dynamic angle mode.

pnpm add pray-calc

Quick start

import { getPrayerTimes } from 'pray-calc'

const times = getPrayerTimes({
  date: new Date(),
  latitude: 41.4993,
  longitude: -81.6944,
  timezone: 'America/New_York',
  method: 'ISNA',
})

console.log(times.fajr)    // e.g. "05:34"
console.log(times.dhuhr)   // e.g. "13:02"
console.log(times.asr)     // e.g. "16:28"
console.log(times.maghrib) // e.g. "19:47"
console.log(times.isha)    // e.g. "21:12"

nrel-spa

TypeScript port of the NREL Solar Position Algorithm. Used internally by pray-calc.

pnpm add nrel-spa

Quick start

import { computeSolarPosition } from 'nrel-spa'

const pos = computeSolarPosition({
  date: new Date(),
  latitude: 41.4993,
  longitude: -81.6944,
  elevation: 200,       // metres above sea level
  pressure: 1013.25,    // millibars
  temperature: 15,      // °C
  deltaT: 69.18,        // seconds (ΔT for 2025)
})

console.log(pos.topocentricAltitude)   // degrees above horizon
console.log(pos.topocentricAzimuth)    // degrees clockwise from north

moon-sighting

JPL DE442S-based lunar crescent visibility. Requires downloading the kernel file separately (see package README).

pnpm add moon-sighting

Quick start

import { getMoonSightingReport } from 'moon-sighting'

const report = await getMoonSightingReport({
  date: new Date('2025-03-01'),
  latitude: 21.3891,
  longitude: 39.8579,   // Mecca
})

console.log(report.yallopCriteria)   // 'A' | 'B' | 'C' | 'D' | 'F'
console.log(report.odehCriteria)     // 'visible' | 'not-visible' | 'marginal'

moon-cycle

Maps any date/time to a NASA SVS moon phase image frame.

pnpm add moon-cycle

Quick start

import { cycleMonth, cdnUrl } from 'moon-cycle'

const frames = cycleMonth({ year: 2025, month: 3 })
const imageUrl = cdnUrl(frames[0])
console.log(imageUrl)  // jsDelivr CDN URL for the frame image

hijri-core

Zero-dependency Hijri calendar engine.

pnpm add hijri-core

Quick start

import { toHijri, toGregorian } from 'hijri-core'

const hijri = toHijri(new Date('2025-03-29'))
console.log(hijri)  // { year: 1446, month: 9, day: 29 }

const greg = toGregorian({ year: 1446, month: 10, day: 1 })
console.log(greg)   // Date object: 2025-03-30

luxon-hijri

Hijri/Gregorian conversion with Luxon. Requires luxon as a peer dependency.

pnpm add luxon-hijri luxon

Quick start

import { toHijri, formatHijriDate } from 'luxon-hijri'
import { DateTime } from 'luxon'

const dt = DateTime.fromISO('2025-03-29')
const hijri = toHijri(dt)
console.log(hijri)  // { year: 1446, month: 9, day: 29 }

const formatted = formatHijriDate(dt, 'iD iMMMM iYYYY')
console.log(formatted)  // e.g. "29 Ramadan 1446"