index.js
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var parse = require('../parse/index.js')
var differenceInCalendarDays = require('../difference_in_calendar_days/index.js')
var compareAsc = require('../compare_asc/index.js')
/**
* @category Day Helpers
* @summary Get the number of full days between the given dates.
*
* @description
* Get the number of full days between the given dates.
*
* @param {Date|String|Number} dateLeft - the later date
* @param {Date|String|Number} dateRight - the earlier date
* @returns {Number} the number of full days
*
* @example
* // How many full days are between
* // 2 July 2011 23:00:00 and 2 July 2012 00:00:00?
* var result = differenceInDays(
* new Date(2012, 6, 2, 0, 0),
* new Date(2011, 6, 2, 23, 0)
* )
* //=> 365
*/
function differenceInDays (dirtyDateLeft, dirtyDateRight) {
var dateLeft = parse(dirtyDateLeft)
var dateRight = parse(dirtyDateRight)
var sign = compareAsc(dateLeft, dateRight)
var difference = Math.abs(differenceInCalendarDays(dateLeft, dateRight))
dateLeft.setDate(dateLeft.getDate() - sign * difference)
// Math.abs(diff in full days - diff in calendar days) === 1 if last calendar day is not full
// If so, result must be decreased by 1 in absolute value
var isLastDayNotFull = compareAsc(dateLeft, dateRight) === -sign
return sign * (difference - isLastDayNotFull)
}
module.exports = differenceInDays