index.js
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import toDate from '../toDate/index.js';
import startOfISOWeek from '../startOfISOWeek/index.js';
import startOfISOWeekYear from '../startOfISOWeekYear/index.js';
import requiredArgs from '../_lib/requiredArgs/index.js';
var MILLISECONDS_IN_WEEK = 604800000;
/**
* @name getISOWeek
* @category ISO Week Helpers
* @summary Get the ISO week of the given date.
*
* @description
* Get the ISO week 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 ISO week
* @throws {TypeError} 1 argument required
*
* @example
* // Which week of the ISO-week numbering year is 2 January 2005?
* var result = getISOWeek(new Date(2005, 0, 2))
* //=> 53
*/
export default function getISOWeek(dirtyDate) {
requiredArgs(1, arguments);
var date = toDate(dirtyDate);
var diff = startOfISOWeek(date).getTime() - startOfISOWeekYear(date).getTime(); // Round the number of days 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) + 1;
}