54 lines
1.9 KiB
JavaScript
54 lines
1.9 KiB
JavaScript
import toDate from '../toDate/index.js';
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import differenceInCalendarDays from '../differenceInCalendarDays/index.js';
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import compareAsc from '../compareAsc/index.js';
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/**
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* @name differenceInDays
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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 day periods between the given dates.
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*
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* ### v2.0.0 breaking changes:
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*
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* - [Changes that are common for the whole library](https://github.com/date-fns/date-fns/blob/master/docs/upgradeGuide.md#Common-Changes).
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*
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* @param {Date|Number} dateLeft - the later date
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* @param {Date|Number} dateRight - the earlier date
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* @returns {Number} the number of full days
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* @throws {TypeError} 2 arguments required
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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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* // How many days are between
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* // 2 July 2011 23:59:00 and 3 July 2011 00:01:00?
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* var result = differenceInDays(
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* new Date(2011, 6, 3, 0, 1),
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* new Date(2011, 6, 2, 23, 59)
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* )
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* //=> 0
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*/
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export default function differenceInDays(dirtyDateLeft, dirtyDateRight) {
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if (arguments.length < 2) {
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throw new TypeError('2 arguments required, but only ' + arguments.length + ' present');
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}
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var dateLeft = toDate(dirtyDateLeft);
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var dateRight = toDate(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); // 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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var result = sign * (difference - isLastDayNotFull); // Prevent negative zero
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return result === 0 ? 0 : result;
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} |