Important

Now calculations doesn't follow time adjustments for nepal timezone. finding first day of month may have 1 day off or 1 day more since julian day and ahar(julian apoach) is in Greenwich Mean Time ‎(UTC)‎. thanks @aj3sh for testing those discrepancies. conversation 🔗

ℹ️ Observations after reviewing possible fixes 20250110:

1. The ahar value( julian day count) is based on Ujjain timezone. (ancient UTC of astrology).

2. Nepal's time zone has not been consistent and has changed over time. To obtain accurate results for past dates, the exact time zone and location, along with the date of the change, are required. https://en.m.wikipedia.org/wiki/Nepal_Standard_Time .

3. It is unclear whether calculations for the Bikram Sambat date in Nepal now uses Kathmandu's latitude and longitude or the Nepal Standard Time Zone's reference location.

Understanding the specific location and time zone used is crucial for accurate results. Changes in time and location can affect day or month transitions, potentially causing misalignment with pre-calculated data.

Bikram-JS

Bikram-js is an npm package for converting Gregorian dates to Bikram Sambat dates, calculating Tithis, and providing various functionalities related to the Bikram Sambat calendar. This package is useful for developers needing accurate Nepali date conversions and Tithi calculations in their applications.

Repository Structure

• Root Folder: Contains the source code for the bikram-js npm package.
• example Folder: Contains an example implementation of a calendar and date converter to demonstrate the use of the bikram-js package.

Features

• Convert Gregorian dates to Bikram Sambat dates and vice versa
• Calculate Tithi (lunar day) for a given Gregorian date and longitude
• Retrieve Nepali month and weekday names

Installation

You can install the package via npm:

npm install bikram-js
# Or for development purposes:
npm install bikram-js --save-dev

Usage

Bikram and Tithi Class

The Bikram class provides methods for converting between Gregorian and Bikram Sambat dates and retrieving Nepali month and weekday names.

Example

Usage Examples (these examples are in test section of this package too)

Here are some examples of how to use the bikram-js package:

Convert Gregorian Date to Bikram Sambat

import { Bikram } from 'bikram-js';

const bikram = new Bikram();
bikram.fromGregorian(2024, 1, 1);

console.log(bikram.getYear());  // 2080
console.log(bikram.getMonth()); // 9
console.log(bikram.getDay());   // 16

Calculate Tithi

import { Tithi } from 'bikram-js';

const testTithi = new Tithi();
const tithiResult = testTithi.calculateTithi(2024, 1, 1);

console.log(tithiResult.tithi); // "पञ्चमी"
console.log(tithiResult.paksha); // "कृष्ण"

Convert Bikram Sambat Date to Gregorian

import { Bikram } from 'bikram-js';

const bikram = new Bikram();
const gregorianDate = bikram.toGregorian(2081, 1, 1);

console.log(gregorianDate.year);  // 2024
console.log(gregorianDate.month); // 4
console.log(gregorianDate.day);   // 13

Calculate Total Days in Bikram Month

import { Bikram } from 'bikram-js';

const bikram = new Bikram();
const totalDays = bikram.daysInMonth(2081, 8);
console.log(totalDays); // 30

const totalDaysFebruary = bikram.daysInMonth(2081, 2);
console.log(totalDaysFebruary); // 32

Calculate Tithi for Leap Year

import { Tithi } from 'bikram-js';

const testTithi = new Tithi();
const tithiResult = testTithi.calculateTithi(2020, 2, 29);

console.log(tithiResult.tithi); // "पञ्चमी"
console.log(tithiResult.paksha); // "शुक्ल"

Get Nepali Weekday Name from Gregorian Date

import { Bikram } from 'bikram-js';

const bikram = new Bikram();
console.log(bikram.getWeekdayName(2024, 12, 5)); // 'बिहीबार'
console.log(bikram.getWeekdayName(2024, 12, 6)); // 'शुक्रबार' 
console.log(bikram.getWeekdayName(2024, 12, 7)); // 'शनिबार'
console.log(bikram.getWeekdayName(2024, 12, 8)); // 'आइतबार'

Get Nepali Weekday Name from Bikram Sambat Date

import { Bikram } from 'bikram-js';

const bikram = new Bikram();
const gregorianDate = bikram.toGregorian(2081, 8, 20);
const testDay = bikram.getWeekdayName(gregorianDate.year, gregorianDate.month, gregorianDate.day);
console.log(testDay); // "बिहीबार"

Handle Leap Years Correctly

import { Bikram } from 'bikram-js';

const bikram = new Bikram();
console.log(bikram.getWeekdayName(2020, 2, 29)); // 'शनिबार'

Handle Edge Cases Correctly

import { Bikram } from 'bikram-js';

const bikram = new Bikram();
console.log(bikram.getWeekdayName(2024, 1, 1)); // 'सोमबार'
console.log(bikram.getWeekdayName(2024, 12, 31)); // 'मंगलबार'

Get Nepali Month Name for a Given Gregorian Date

import { Bikram } from 'bikram-js';

const bikram = new Bikram();
bikram.fromGregorian(2024, 12, 5);
const testMonthName = bikram.getMonthName(bikram.getMonth());
console.log(testMonthName); // 'मंसिर'

Handle Invalid Month Numbers Gracefully

import { Bikram } from 'bikram-js';

const bikram = new Bikram();
try {
    bikram.getMonthName(0);
} catch (error) {
    console.error(error);
}
try {
    bikram.getMonthName(13);
} catch (error) {
    console.error(error);
}

Documentation

Detailed documentation of functions are available in the docs/docs folder or here . You can find comprehensive guides and examples on using the bikram-js library.

To view the documentation:

1. Navigate to the docs/docs folder.
2. Open the markdown files to read the documentation.

License

This project is licensed under the GNU General Public License v3.0. See the LICENSE file for more details.

Contributing

Contributions are welcome! you can fork this repo, create modifications and send pull request.

Acknowledgements

The Bikram Sambat and Tithi functionalities are implemented using calculations from a port of the Perl script Pancanga library by M. Fushimi and M. Yano. For detailed information, consult the original documentation:

• Documentation
• Pancanga Library

Special thanks to Samar Dhwoj Acharya (techgaun), Kapil Karki (kapil-31), and the Build For Nepal team for their encouragement.

Author

Khumnath CG ([email protected])

Contributors

Special thanks to all contributors.