lunar-date-calculator

lunar-date-calculator is a Javascript library for converting the date to the solar date in the current or any target year.

Installation

Use 'npm' to install the package.

npm i lunar-date-calculator

Definition

Lunar Calendar

A lunar calendar is a calendar based on the monthly cycles of the Moon's phases (synodic months, lunations), in contrast to solar calendars, whose annual cycles are based only directly on the solar year.

From wikipedia

Solar Calendar

A solar calendar is a calendar whose dates indicate the season or almost equivalently the apparent position of the Sun relative to the stars. The Gregorian calendar, widely accepted as a standard in the world, is an example of a solar calendar.

From wikipedia

Usage

fromSolarDate(solarYear, solarMonth, solarDay, targetYear = currentYear)

This function converts dates two times to get the solar date in the currentYear or any targetYear.

A targetYear is an optional parameter so that if targetYear is undefined, the default value is currentYear.

First, it converts the solar date to the lunar date in solarYear.

If targetYear is defined, it converts the caculated lunar date to the solar date in the targetYear.

Otherwise, it converts the lunar date to the solar date in currentYear.

import lunaDateCalculator from 'lunar-date-calculator';

// convert solar to lunar date in the current year (default value)
const solar2CurrentLunar = lunaDateCalculator.fromSolarDate(2007, 4, 18);
// output: { year: 2022, month: 4, day: 2 }

// convert solar in the future to lunar date in the target year
const solarInFuture2TargetLunar = lunaDateCalculator.fromSolarDate(2007, 4, 18, 1999);
// output: { year: 1999, month: 4, day: 17 }

// convert solar in the past to lunar date in the target year
const solarInPast2TargetLunar = lunaDateCalculator.fromSolarDate(2019, 4, 18, 2021);
// output: { year: 2021, month: 4, day: 13 }

fromLunarDate(lunarYear, lunarMonth, lunarDay, targetYear = currentYear)

This function converts the lunar date to the solar date in the currentYear or any targetYear.

A targetYear is an optional parameter so that if targetYear is undefined, the default value is currentYear.

import lunaDateCalculator from 'lunar-date-calculator';

// convert lunar to lunar date in the current year (default value)
const lunar2CurrentLunar = lunaDateCalculator.fromLunarDate(2007, 5, 15);
// output: { year: 2022, month: 6, day: 13 }

// convert lunar in the future to lunar date in the target year
const lunarInFuture2TargetLunar = lunaDateCalculator.fromLunarDate(2007, 5, 15, 1999);
// output: { year: 1999, month: 6, day: 28 }

// convert lunar in the past to lunar date in the target year
const lunarInPast2TargetLunar = lunaDateCalculator.fromLunarDate(2007, 5, 15, 2019);
// output: { year: 2019, month: 6, day: 17 }