103 lines
3.2 KiB
JavaScript
103 lines
3.2 KiB
JavaScript
var dateUtils = (function (exports) {
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'use strict';
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function stripTime(timeValue) {
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return new Date(timeValue).setHours(0, 0, 0, 0);
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}
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function today() {
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return new Date().setHours(0, 0, 0, 0);
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}
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// Get the time value of the start of given date or year, month and day
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function dateValue(...args) {
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switch (args.length) {
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case 0:
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return today();
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case 1:
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return stripTime(args[0]);
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}
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// use setFullYear() to keep 2-digit year from being mapped to 1900-1999
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const newDate = new Date(0);
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newDate.setFullYear(...args);
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return newDate.setHours(0, 0, 0, 0);
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}
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function addDays(date, amount) {
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const newDate = new Date(date);
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return newDate.setDate(newDate.getDate() + amount);
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}
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function addWeeks(date, amount) {
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return addDays(date, amount * 7);
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}
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function addMonths(date, amount) {
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// If the day of the date is not in the new month, the last day of the new
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// month will be returned. e.g. Jan 31 + 1 month → Feb 28 (not Mar 03)
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const newDate = new Date(date);
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const monthsToSet = newDate.getMonth() + amount;
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let expectedMonth = monthsToSet % 12;
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if (expectedMonth < 0) {
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expectedMonth += 12;
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}
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const time = newDate.setMonth(monthsToSet);
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return newDate.getMonth() !== expectedMonth ? newDate.setDate(0) : time;
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}
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function addYears(date, amount) {
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// If the date is Feb 29 and the new year is not a leap year, Feb 28 of the
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// new year will be returned.
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const newDate = new Date(date);
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const expectedMonth = newDate.getMonth();
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const time = newDate.setFullYear(newDate.getFullYear() + amount);
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return expectedMonth === 1 && newDate.getMonth() === 2 ? newDate.setDate(0) : time;
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}
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// Calculate the distance bettwen 2 days of the week
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function dayDiff(day, from) {
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return (day - from + 7) % 7;
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}
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// Get the date of the specified day of the week of given base date
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function dayOfTheWeekOf(baseDate, dayOfWeek, weekStart = 0) {
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const baseDay = new Date(baseDate).getDay();
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return addDays(baseDate, dayDiff(dayOfWeek, weekStart) - dayDiff(baseDay, weekStart));
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}
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// Get the ISO week of a date
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function getWeek(date) {
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// start of ISO week is Monday
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const thuOfTheWeek = dayOfTheWeekOf(date, 4, 1);
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// 1st week == the week where the 4th of January is in
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const firstThu = dayOfTheWeekOf(new Date(thuOfTheWeek).setMonth(0, 4), 4, 1);
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return Math.round((thuOfTheWeek - firstThu) / 604800000) + 1;
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}
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// Get the start year of the period of years that includes given date
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// years: length of the year period
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function startOfYearPeriod(date, years) {
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/* @see https://en.wikipedia.org/wiki/Year_zero#ISO_8601 */
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const year = new Date(date).getFullYear();
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return Math.floor(year / years) * years;
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}
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exports.addDays = addDays;
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exports.addMonths = addMonths;
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exports.addWeeks = addWeeks;
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exports.addYears = addYears;
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exports.dateValue = dateValue;
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exports.dayOfTheWeekOf = dayOfTheWeekOf;
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exports.getWeek = getWeek;
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exports.startOfYearPeriod = startOfYearPeriod;
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exports.stripTime = stripTime;
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exports.today = today;
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Object.defineProperty(exports, '__esModule', { value: true });
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return exports;
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})({});
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