69 lines
2.5 KiB
JavaScript
69 lines
2.5 KiB
JavaScript
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"use strict";
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exports.getOverlappingDaysInIntervals = getOverlappingDaysInIntervals;
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var _index = require("./_lib/getTimezoneOffsetInMilliseconds.js");
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var _index2 = require("./constants.js");
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var _index3 = require("./toDate.js");
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/**
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* @name getOverlappingDaysInIntervals
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* @category Interval Helpers
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* @summary Get the number of days that overlap in two time intervals
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*
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* @description
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* Get the number of days that overlap in two time intervals. It uses the time
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* between dates to calculate the number of days, rounding it up to include
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* partial days.
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*
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* Two equal 0-length intervals will result in 0. Two equal 1ms intervals will
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* result in 1.
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*
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* @typeParam DateType - The `Date` type, the function operates on. Gets inferred from passed arguments. Allows to use extensions like [`UTCDate`](https://github.com/date-fns/utc).
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*
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* @param intervalLeft - The first interval to compare.
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* @param intervalRight - The second interval to compare.
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*
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* @returns The number of days that overlap in two time intervals
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*
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* @example
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* // For overlapping time intervals adds 1 for each started overlapping day:
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* getOverlappingDaysInIntervals(
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* { start: new Date(2014, 0, 10), end: new Date(2014, 0, 20) },
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* { start: new Date(2014, 0, 17), end: new Date(2014, 0, 21) }
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* )
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* //=> 3
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*
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* @example
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* // For non-overlapping time intervals returns 0:
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* getOverlappingDaysInIntervals(
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* { start: new Date(2014, 0, 10), end: new Date(2014, 0, 20) },
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* { start: new Date(2014, 0, 21), end: new Date(2014, 0, 22) }
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* )
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* //=> 0
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*/
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function getOverlappingDaysInIntervals(intervalLeft, intervalRight) {
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const [leftStart, leftEnd] = [
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+(0, _index3.toDate)(intervalLeft.start),
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+(0, _index3.toDate)(intervalLeft.end),
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].sort((a, b) => a - b);
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const [rightStart, rightEnd] = [
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+(0, _index3.toDate)(intervalRight.start),
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+(0, _index3.toDate)(intervalRight.end),
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].sort((a, b) => a - b);
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// Prevent NaN result if intervals don't overlap at all.
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const isOverlapping = leftStart < rightEnd && rightStart < leftEnd;
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if (!isOverlapping) return 0;
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// Remove the timezone offset to negate the DST effect on calculations.
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const overlapLeft = rightStart < leftStart ? leftStart : rightStart;
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const left =
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overlapLeft - (0, _index.getTimezoneOffsetInMilliseconds)(overlapLeft);
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const overlapRight = rightEnd > leftEnd ? leftEnd : rightEnd;
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const right =
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overlapRight - (0, _index.getTimezoneOffsetInMilliseconds)(overlapRight);
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// Ceil the number to include partial days too.
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return Math.ceil((right - left) / _index2.millisecondsInDay);
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}
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