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index.js
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index.js
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import getTimezoneOffsetInMilliseconds from '../_lib/getTimezoneOffsetInMilliseconds/index.js'
import startOfDay from '../startOfDay/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.
*
* @param {Date|String|Number} dateLeft - the later date
* @param {Date|String|Number} dateRight - the earlier date
* @param {Options} [options] - the object with options. See [Options]{@link https://date-fns.org/docs/Options}
* @param {0|1|2} [options.additionalDigits=2] - passed to `toDate`. See [toDate]{@link https://date-fns.org/docs/toDate}
* @returns {Number} the number of calendar days
* @throws {TypeError} 2 arguments required
* @throws {RangeError} `options.additionalDigits` must be 0, 1 or 2
*
* @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, 2, 0, 1),
* new Date(2011, 6, 2, 23, 59)
* )
* //=> 1
*/
export default function differenceInCalendarDays (dirtyDateLeft, dirtyDateRight, dirtyOptions) {
if (arguments.length < 2) {
throw new TypeError('2 arguments required, but only ' + arguments.length + ' present')
}
var startOfDayLeft = startOfDay(dirtyDateLeft, dirtyOptions)
var startOfDayRight = startOfDay(dirtyDateRight, dirtyOptions)
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)
}