leap-year-finder

leap-year-finder is a simple JavaScript library that provides functions for calculating leap years.

Install

$ npm install @gennyboy/leap-year-finder

Usage

To use the package, import the desired functions and call them with the appropriate arguments.

import { isLeapYear, getNextLeapYear } from "@gennyboy/leap-year-finder";

isLeapYear(2020); // true
getNextLeapYear(2020); // 2024

API

isLeapYear(year)

Returns true if the given year is a leap year, false otherwise.

year

The year to check. If not specified, the current year is used.

Must be a number or a Date object.

isLeapYear(2020);
//=> true

isLeapYear(2021);
//=> false

isLeapYear(); // Check if the current year is a leap year or not.

isCurrentYearLeap()

Returns true if the current year is a leap year, false otherwise.

// Executes in 2020
isCurrentYearLeap();
//=> true

// Executes in 2021
isCurrentYearLeap();
//=> false

getNextLeapYear(year)

Returns the next leap year after the given year (or the current year if not specified).

year

The year to check. If not specified, the current year is used.

Must be a number or a Date object.

getNextLeapYear(2019);
//=> 2020

getNextLeapYear(2020);
//=> 2024

// Executes in 2019
getNextLeapYear();
//=> 2020

getPreviousLeapYear(year)

Returns the previous leap year before the given year (or the current year if not specified).

year

The year to check. If not specified, the current year is used.

Must be a number or a Date object.

getPreviousLeapYear(2021);
//=> 2020

getPreviousLeapYear(2020);
//=> 2016

// Executes in 2021
getPreviousLeapYear();
//=> 2020

getNextLeapYears(numberOfYears, year)

Returns an array of the next numberOfYears leap years after the given year (or the current year if not specified).

numberOfYears

The number of leap years to return.

Must be a number in range of 1 to 10.

year

The year to check. If not specified, the current year is used.

Must be a number or a Date object.

getNextLeapYears(3, 2020);
//=> [2024, 2028, 2032]

getNextLeapYears(3, 2019);
//=> [2020, 2024, 2028]

// Executes in 2019
getNextLeapYears(3);
//=> [2020, 2024, 2028]

getPreviousLeapYears(numberOfYears, year)

Returns an array of the previous numberOfYears leap years before the given year (or the current year if not specified).

numberOfYears

The number of leap years to return.

Must be a number in range of 1 to 10.

year

The year to check. If not specified, the current year is used.

Must be a number or a Date object.

getPreviousLeapYears(3, 2020);
//=> [2016, 2012, 2008]

getPreviousLeapYears(3, 2021);
//=> [2020, 2016, 2012]

// Executes in 2021
getPreviousLeapYears(3);
//=> [2020, 2016, 2012]

getDateForLastDayOfFebruary(year)

Returns the date object for the last day of February for the given year (or the current year if not specified).

year

The year to check. If not specified, the current year is used.

Must be a number or a Date object.

getDateForLastDayOfFebruary(2020);
//=> Sat Feb 29 2020 00:00:00 GMT+0900

getDateForLastDayOfFebruary(2021);
//=> Sun Feb 28 2021 00:00:00 GMT+0900

// Executes in 2021
getDateForLastDayOfFebruary();
//=> Sun Feb 28 2021 00:00:00 GMT+0900

getDateForNextLeapYearLastDayOfFebruary()

Returns the date object for the last day of February for the next leap year.

// Executes in 2019
getDateForNextLeapYearLastDayOfFebruary();
//=> Sat Feb 29 2020 00:00:00 GMT+0900

// Executes in 2020
getDateForNextLeapYearLastDayOfFebruary();
//=> Sat Feb 29 2024 00:00:00 GMT+0900

getDateForPreviousLeapYearLastDayOfFebruary()

Returns the date object for the last day of February for the previous leap year.

// Executes in 2021
getDateForPreviousLeapYearLastDayOfFebruary();
//=> Sun Feb 28 2020 00:00:00 GMT+0900

// Executes in 2020
getDateForPreviousLeapYearLastDayOfFebruary();
//=> Sun Feb 28 2016 00:00:00 GMT+0900