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Diffstat (limited to 'node_modules/date-fns/esm/getISOWeekYear/index.js')
| -rw-r--r-- | node_modules/date-fns/esm/getISOWeekYear/index.js | 43 |
1 files changed, 43 insertions, 0 deletions
diff --git a/node_modules/date-fns/esm/getISOWeekYear/index.js b/node_modules/date-fns/esm/getISOWeekYear/index.js new file mode 100644 index 0000000..494af86 --- /dev/null +++ b/node_modules/date-fns/esm/getISOWeekYear/index.js @@ -0,0 +1,43 @@ +import toDate from "../toDate/index.js"; +import startOfISOWeek from "../startOfISOWeek/index.js"; +import requiredArgs from "../_lib/requiredArgs/index.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 + * + * @param {Date|Number} date - the given date + * @returns {Number} the ISO week-numbering year + * @throws {TypeError} 1 argument required + * + * @example + * // Which ISO-week numbering year is 2 January 2005? + * const result = getISOWeekYear(new Date(2005, 0, 2)) + * //=> 2004 + */ +export default function getISOWeekYear(dirtyDate) { + requiredArgs(1, arguments); + var date = toDate(dirtyDate); + var year = date.getFullYear(); + var fourthOfJanuaryOfNextYear = new Date(0); + fourthOfJanuaryOfNextYear.setFullYear(year + 1, 0, 4); + fourthOfJanuaryOfNextYear.setHours(0, 0, 0, 0); + var startOfNextYear = startOfISOWeek(fourthOfJanuaryOfNextYear); + var fourthOfJanuaryOfThisYear = new Date(0); + fourthOfJanuaryOfThisYear.setFullYear(year, 0, 4); + fourthOfJanuaryOfThisYear.setHours(0, 0, 0, 0); + var startOfThisYear = 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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