bc518174
 王天杨
提交两个项目文件
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"use strict";
exports.getISOWeekYear = getISOWeekYear;
var _index = require("./constructFrom.js");
var _index2 = require("./startOfISOWeek.js");
var _index3 = require("./toDate.js");
/**
* @name getISOWeekYear
* @category ISO Week-Numbering Year Helpers
* @summary Get the ISO week-numbering year of the given date.
*
* @description
* Get the ISO week-numbering year of the given date,
* which always starts 3 days before the year's first Thursday.
*
* ISO week-numbering year: http://en.wikipedia.org/wiki/ISO_week_date
*
* @typeParam DateType - The `Date` type, the function operates on. Gets inferred from passed arguments. Allows to use extensions like [`UTCDate`](https://github.com/date-fns/utc).
*
* @param date - The given date
*
* @returns The ISO week-numbering year
*
* @example
* // Which ISO-week numbering year is 2 January 2005?
* const result = getISOWeekYear(new Date(2005, 0, 2))
* //=> 2004
*/
function getISOWeekYear(date) {
const _date = (0, _index3.toDate)(date);
const year = _date.getFullYear();
const fourthOfJanuaryOfNextYear = (0, _index.constructFrom)(date, 0);
fourthOfJanuaryOfNextYear.setFullYear(year + 1, 0, 4);
fourthOfJanuaryOfNextYear.setHours(0, 0, 0, 0);
const startOfNextYear = (0, _index2.startOfISOWeek)(
fourthOfJanuaryOfNextYear,
);
const fourthOfJanuaryOfThisYear = (0, _index.constructFrom)(date, 0);
fourthOfJanuaryOfThisYear.setFullYear(year, 0, 4);
fourthOfJanuaryOfThisYear.setHours(0, 0, 0, 0);
const startOfThisYear = (0, _index2.startOfISOWeek)(
fourthOfJanuaryOfThisYear,
);
if (_date.getTime() >= startOfNextYear.getTime()) {
return year + 1;
} else if (_date.getTime() >= startOfThisYear.getTime()) {
return year;
} else {
return year - 1;
}
}
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