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README.md

nanakshahi-js

A JavaScript Library to get Nanakshahi Dates and Gurpurabs

npm Travis (.org) GitHub license GitHub issues GitHub pull requests jsdelivr

Contents

Usage

NPM

Install the library via NPM:

npm install nanakshahi

The library can be imported into Node as below:

const n = require('nanakshahi')

const date = new Date()

n.getNanakshahiDate( date )
n.getDateFromNanakshahi( 550, 10, 23 )
n.getHolidaysForDay( date )
n.getHolidaysForMonth( 1 )
n.findMovableHoliday( 'gurunanak' )
n.findBikramiFromDate( date )
n.findDateFromBikramiLunar( 1723, 10, 7 )
n.findDateFromBikramiSolar( 1723, 9, 23 )

Want a demo?
Try on RunKit

CDN

Additionally, the package is available for web use via unpkg CDN.

<script src="https://unpkg.com/nanakshahi"></script>

Or via jsDelivr

<script src="https://cdn.jsdelivr.net/npm/nanakshahi/dist/index.min.js"></script>

Notes

Nanakshahi Calendar

This library is based of the Nanakshahi Calendar passed by Sri Akal Takht Sahib in 2003 CE.

All Gurpurabs and Historical dates are reckoned with their Solar Dates. An exception to this are the Movable Lunar dates which are to be reckoned using the Bikrami calender until further Panthic consensus.

The Nanakshahi functions will only calculate dates after Nanakshahi adoption in 2003 CE. Any dates before March 14, 2003 CE (535 NS) will return with an Out of Range error.

Bikrami

The Bikrami functions in this library were implemented to automatically calculate the Movable dates for the original Nanakshahi Calendar.

The functions are also provided as reference for researchers and historians. No support will be given to anyone attempting to build a calendar from these functions.

The accuracy of the Bikrami calculations match the dates given in Jantri 500 Years by Pal Singh Purewal and this library has been checked personally by Pal Singh Purewal himself.

JavaScript Date() Object

In this library, the Date object has been given in local time of the client. This ensures that the Gregorian date calculated by the functions are correct regardless of Timezone.

The only exception is when the Date is given in UTC for the Astro Times function, Bikrami Lunar Tithi Start/End times, and Sankranti Moment time.

API

getDateFromNanakshahi(year, month, date)

Converts Nanakshahi Date into the Gregorian Calendar

Returns: Object - Gregorian Date + Nanakshahi Date in English and Punjabi

Param Type Description
year number Nanakshahi Year
month number Nanakshahi Month, 1-12
date number Nanakshahi Day

Example

getDateFromNanakshahi( 550, 10, 23 )

getHolidaysForDay([gregorianDate])

Returns all Gurpurabs and Holidays for a Date

Returns: Array - Holidays for the day with Date and name in English and Punjabi

Param Type Default Description
[gregorianDate] Object new Date() JavaScript Date() Object

Example

getHolidaysForDay( new Date() )

getHolidaysForMonth(month, [year])

Returns all Gurpurabs and Holidays for a Nanakshahi Month

Returns: Object - Holidays for the month with Date and name in English and Punjabi

Param Type Description
month number Nanakshahi Month, 1-12
[year] number Nanakshahi Year. Default is current Nanakshahi Year.

Example

getHolidaysForMonth( 1 )

getNanakshahiDate([gregorianDate])

Converts given Gregorian Date to the corresponding date in the Nanakshahi Calendar

Returns: Object - Nanakshahi Date in English and Punjabi

Param Type Default Description
[gregorianDate] Object new Date() JavaScript Date() Object

Example

getNanakshahiDate( new Date() )

findMovableHoliday(holiday, [year])

Returns Gregorian Date of Movable Holiday

Returns: Object - Holiday Date with Name in English and Punjabi

Param Type Description
holiday string Movable Holidays:
gurunanak - Parkash Guru Nanak Dev Ji
bandishhorr - Bandi Shhorr Divas / Diwali
holla - Holla Mahalla
kabeer - Birthday Bhagat Kabeer Ji
ravidaas - Birthday Bhagat Ravidaas Ji
naamdev - Birthday Bhagat Naamdev Ji
[year] number Gregorian year, default is current year.

Example

findMovableHoliday( 'gurunanak' )

calculateAstroTimes([date])

Calculates astronomical times for the Sun and Moon (at Amritsar)

Returns: Object - Astronomical values for the Sun and Moon in Universal Time.

Param Type Default Description
[date] Object new Date() JavaScript Date() Object

Example

calculateAstroTimes( new Date() )

findBikramiFromDate(date, [options])

Returns given date to the corresponding date in the Bikrami Calendar

Returns: Object - Bikrami (Includes Lunar and Solar Date)

Param Type Default Description
date Object JavaScript Date() Object
[options] Object { astro: true } [astro=true] - Set to false to use Surya Sidhantta instead of Drik Gannit
[isJulian] - Set to true if entered date is in Julian Calendar

Example

findBikramiFromDate( new Date() )

findDateFromBikramiLunar(year, month, date, [options])

Converts Bikrami Lunar Date into the Gregorian Calendar

Returns: Object - Gregorian Date

Param Type Default Description
year number Bikrami Year
month number Bikrami Month
date number Bikrami Tithi
[options] Object { astro: true } [astro=true] - Set to false to use Surya Sidhantta instead of Drik Gannit
[paksh] - Lunar Paksh. Default is Sudi, true for Vadi.
[leapMonth] - Set to true if the month is Adhika Month (Mal Maas)
[leapDay] - Set to true if the lunar day spans more than 1 solar day

Example

findDateFromBikramiLunar( 1723, 10, 7 )

findDateFromBikramiSolar(year, month, date, [options])

Converts Bikrami Solar Date into the Gregorian Calendar

Returns: Object - Gregorian Date

Param Type Default Description
year number Bikrami Year
month number Bikrami Month
date number Bikrami Day
[options] Object { astro: true } [astro=true] Set to false to use Surya Sidhantta instead of Drik Gannit

Example

findDateFromBikramiSolar( 1723, 9, 23 )

Acknowledgements

I want to thank:

  • Guru Sahib, who inspires us into Sikhi.

  • Pal Singh Purewal, who explained various concepts in the Bikrami and Nanakshahi Calendars to me and answered my various technical and historical questions. Spent countless hours verifying the calculations done by me.

  • E. M. Reingold and N. Dershowitz for their Calendrical Calculations book and their mathematical functions, which serve as the base for the Bikrami calculations done in this library.

  • My father, Jasjit Singh, whose curiosity in the Nanakshahi and Bikrami calendar systems inspired me find answers to his technical questions.

Contributing

We're happy to accept suggestions and pull requests!

To get started, clone this repo and run npm install inside this directory.

This repository follows the Airbnb's Javascript Style Guide, with a few minor modifications. Notably, spaces should be included inside parentheses and brackets (weird, right!). An ESLint file is provided, and your code will automatically be checked on-commit for style. It is recommended to install an ESLint plugin for your editor (VS Code's ESLint plugin works out of the box), so you can receive linter suggestions as you type.

When writing commit messages, please follow the seven rules. Markdown and HTML JSDoc documentation is generated automatically, on commit, however if you'd like to preview any changes to documentation, npm run build-docs will update README.md. README.md should not be edited, instead apply modifications to README.hbs.

The general workflow for contributing:

  • Fork/create a new branch.
  • Write or update existing tests with expected results
  • Implement functions/changes
  • Add JSDoc function documentation and examples.
  • Create a pull request with the changes.

License

This program is free software: you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation, as per version 3 of the License.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along with this program. If not, see https://www.gnu.org/licenses/.

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