You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
38 lines
1.5 KiB
38 lines
1.5 KiB
import startOfISOWeekYear from '../startOfISOWeekYear/index.js';
|
|
import addWeeks from '../addWeeks/index.js';
|
|
import requiredArgs from '../_lib/requiredArgs/index.js';
|
|
var MILLISECONDS_IN_WEEK = 604800000;
|
|
/**
|
|
* @name getISOWeeksInYear
|
|
* @category ISO Week-Numbering Year Helpers
|
|
* @summary Get the number of weeks in an ISO week-numbering year of the given date.
|
|
*
|
|
* @description
|
|
* Get the number of weeks in an ISO week-numbering year of the given date.
|
|
*
|
|
* ISO week-numbering year: http://en.wikipedia.org/wiki/ISO_week_date
|
|
*
|
|
* ### v2.0.0 breaking changes:
|
|
*
|
|
* - [Changes that are common for the whole library](https://github.com/date-fns/date-fns/blob/master/docs/upgradeGuide.md#Common-Changes).
|
|
*
|
|
* @param {Date|Number} date - the given date
|
|
* @returns {Number} the number of ISO weeks in a year
|
|
* @throws {TypeError} 1 argument required
|
|
*
|
|
* @example
|
|
* // How many weeks are in ISO week-numbering year 2015?
|
|
* var result = getISOWeeksInYear(new Date(2015, 1, 11))
|
|
* //=> 53
|
|
*/
|
|
|
|
export default function getISOWeeksInYear(dirtyDate) {
|
|
requiredArgs(1, arguments);
|
|
var thisYear = startOfISOWeekYear(dirtyDate);
|
|
var nextYear = startOfISOWeekYear(addWeeks(thisYear, 60));
|
|
var diff = nextYear.valueOf() - thisYear.valueOf(); // Round the number of weeks to the nearest integer
|
|
// because the number of milliseconds in a week is not constant
|
|
// (e.g. it's different in the week of the daylight saving time clock shift)
|
|
|
|
return Math.round(diff / MILLISECONDS_IN_WEEK);
|
|
} |