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