easter-date
Version:
Calculate the date of Easter for a given year
54 lines (53 loc) • 1.59 kB
JavaScript
/**
* Returns the date of Easter for a given year.
* Function is an alias for getEasterSunday() function
*
* @example Get Easter date for a given year
* ```ts
* import { getEaster } from "easter-date";
* const easter = getEaster(2023);
* console.log(easter); // 2023-04-09T00:00
* ```
* @param year
*/
export function getEaster(year) {
const a = year % 19;
const b = Math.floor(year / 100);
const c = year % 100;
const d = Math.floor(b / 4);
const e = b % 4; // eslint-disable-line unicorn/prevent-abbreviations
const f = Math.floor((b + 8) / 25);
const g = Math.floor((b - f + 1) / 3);
const h = (19 * a + b - d - g + 15) % 30;
const i = Math.floor(c / 4);
const k = c % 4;
const l = (32 + 2 * e + 2 * i - h - k) % 7;
const m = Math.floor((a + 11 * h + 22 * l) / 451);
const month = Math.floor((h + l - 7 * m + 114) / 31);
const day = ((h + l - 7 * m + 114) % 31) + 1;
return new Date(Date.UTC(year, month - 1, day));
}
/**
* Returns true if the given date is Easter Sunday.
* @param date
*/
export function isEaster(date) {
const easter = getEaster(date.getFullYear());
return (date.getFullYear() === easter.getFullYear() &&
date.getMonth() === easter.getMonth() &&
date.getDate() === easter.getDate());
}
/**
* Returns the date of Easter for a given year.
* @param year
*/
export function getEasterSunday(year) {
return getEaster(year);
}
/**
* Returns true if the given date is Easter Sunday.
* @param date
*/
export function isEasterSunday(date) {
return isEaster(date);
}