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- var getISOYear = require('../get_iso_year/index.js')
- var startOfISOWeek = require('../start_of_iso_week/index.js')
- /**
- * @category ISO Week-Numbering Year Helpers
- * @summary Return the last day of an ISO week-numbering year for the given date.
- *
- * @description
- * Return the last day of an ISO week-numbering year,
- * which always starts 3 days before the year's first Thursday.
- * The result will be in the local timezone.
- *
- * ISO week-numbering year: http://en.wikipedia.org/wiki/ISO_week_date
- *
- * @param {Date|String|Number} date - the original date
- * @returns {Date} the end of an ISO week-numbering year
- *
- * @example
- * // The last day of an ISO week-numbering year for 2 July 2005:
- * var result = lastDayOfISOYear(new Date(2005, 6, 2))
- * //=> Sun Jan 01 2006 00:00:00
- */
- function lastDayOfISOYear (dirtyDate) {
- var year = getISOYear(dirtyDate)
- var fourthOfJanuary = new Date(0)
- fourthOfJanuary.setFullYear(year + 1, 0, 4)
- fourthOfJanuary.setHours(0, 0, 0, 0)
- var date = startOfISOWeek(fourthOfJanuary)
- date.setDate(date.getDate() - 1)
- return date
- }
- module.exports = lastDayOfISOYear
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