index.js
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import getTimezoneOffsetInMilliseconds from '../_lib/getTimezoneOffsetInMilliseconds/index.js';
import startOfDay from '../startOfDay/index.js';
import requiredArgs from '../_lib/requiredArgs/index.js';
var MILLISECONDS_IN_DAY = 86400000;
/**
* @name differenceInCalendarDays
* @category Day Helpers
* @summary Get the number of calendar days between the given dates.
*
* @description
* Get the number of calendar days between the given dates. This means that the times are removed
* from the dates and then the difference in days is calculated.
*
* ### 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} dateLeft - the later date
* @param {Date|Number} dateRight - the earlier date
* @returns {Number} the number of calendar days
* @throws {TypeError} 2 arguments required
*
* @example
* // How many calendar days are between
* // 2 July 2011 23:00:00 and 2 July 2012 00:00:00?
* var result = differenceInCalendarDays(
* new Date(2012, 6, 2, 0, 0),
* new Date(2011, 6, 2, 23, 0)
* )
* //=> 366
* // How many calendar days are between
* // 2 July 2011 23:59:00 and 3 July 2011 00:01:00?
* var result = differenceInCalendarDays(
* new Date(2011, 6, 3, 0, 1),
* new Date(2011, 6, 2, 23, 59)
* )
* //=> 1
*/
export default function differenceInCalendarDays(dirtyDateLeft, dirtyDateRight) {
requiredArgs(2, arguments);
var startOfDayLeft = startOfDay(dirtyDateLeft);
var startOfDayRight = startOfDay(dirtyDateRight);
var timestampLeft = startOfDayLeft.getTime() - getTimezoneOffsetInMilliseconds(startOfDayLeft);
var timestampRight = startOfDayRight.getTime() - getTimezoneOffsetInMilliseconds(startOfDayRight); // Round the number of days to the nearest integer
// because the number of milliseconds in a day is not constant
// (e.g. it's different in the day of the daylight saving time clock shift)
return Math.round((timestampLeft - timestampRight) / MILLISECONDS_IN_DAY);
}