123 lines
2.6 KiB
JavaScript
123 lines
2.6 KiB
JavaScript
'use strict';
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Object.defineProperty(exports, '__esModule', { value: true });
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/**
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* @private
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*/
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function _toYear (year) {
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if (!year) {
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year = new Date().getFullYear();
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} else if (year instanceof Date) {
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year = year.getFullYear();
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} else if (typeof year === 'string') {
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year = parseInt(year, 10);
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}
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return year
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}
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function pre (num, l) {
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l = l || 2;
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const s = '0000' + num;
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return s.substr(s.length - l, l)
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}
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class EasterDate {
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constructor (year, month, day) {
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this.year = year;
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this.month = month;
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this.day = day;
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}
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toString () {
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return [pre(this.year, 4), pre(this.month), pre(this.day)].join('-')
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}
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}
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/**
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* from https://de.wikipedia.org/wiki/Gau%C3%9Fsche_Osterformel
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* ergänzte Formel
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*/
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function _easter (year, julian, gregorian) {
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year = _toYear(year);
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const k = Math.floor(year / 100);
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let m = 15 + Math.floor((3 * k + 3) / 4) - Math.floor((8 * k + 13) / 25);
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let s = 2 - Math.floor((3 * k + 3) / 4);
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if (julian) {
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m = 15;
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s = 0;
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}
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const a = year % 19;
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const d = (19 * a + m) % 30;
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const r = Math.floor((d + a / 11) / 29);
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const og = 21 + d - r;
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const sz = 7 - Math.floor(year + year / 4 + s) % 7;
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const oe = 7 - (og - sz) % 7;
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let os = og + oe;
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if (gregorian) {
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os = os + Math.floor(year / 100) - Math.floor(year / 400) - 2;
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}
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// 1 2 3 4 5 6 7 8
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const daysPerMonth = [0, 31, 28, 31, 30, 31, 30, 31, 31];
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let day = os;
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let month;
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for (month = 3; month < 8; month++) {
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if (day <= daysPerMonth[month]) {
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break
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}
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day -= daysPerMonth[month];
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}
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return new EasterDate(year, month, day)
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}
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/**
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* Calculate easter sunday in the gregorian calendar
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* @param {Date|Number} year
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* @return {EasterDate}
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*/
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function gregorianEaster (year) {
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return _easter(year)
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}
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/**
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* Calculate easter sunday in the gregorian calendar (Shortcut for
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* `gregorianEaster`)
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* @param {Date|Number} year
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* @return {EasterDate}
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*/
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const easter = gregorianEaster;
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/**
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* Calculate easter sunday in the julian calendar
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* @param {Date|Number} year
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* @return {EasterDate}
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*/
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function julianEaster (year) {
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return _easter(year, true)
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}
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/**
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* Orthodox Easter in gregorian calender
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* @param {Date|Number} year
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* @return {EasterDate}
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*/
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function orthodoxEaster (year) {
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return _easter(year, true, true)
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}
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var index = {
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easter,
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gregorianEaster,
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julianEaster,
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orthodoxEaster
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};
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exports.EasterDate = EasterDate;
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exports.default = index;
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exports.easter = easter;
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exports.gregorianEaster = gregorianEaster;
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exports.julianEaster = julianEaster;
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exports.orthodoxEaster = orthodoxEaster;
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