59 lines
1.6 KiB
JavaScript
59 lines
1.6 KiB
JavaScript
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import { toDate } from "./toDate.mjs";
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/**
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* @name closestIndexTo
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* @category Common Helpers
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* @summary Return an index of the closest date from the array comparing to the given date.
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*
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* @description
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* Return an index of the closest date from the array comparing to the given date.
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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 dateToCompare - The date to compare with
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* @param dates - The array to search
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*
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* @returns An index of the date closest to the given date or undefined if no valid value is given
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*
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* @example
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* // Which date is closer to 6 September 2015?
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* const dateToCompare = new Date(2015, 8, 6)
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* const datesArray = [
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* new Date(2015, 0, 1),
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* new Date(2016, 0, 1),
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* new Date(2017, 0, 1)
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* ]
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* const result = closestIndexTo(dateToCompare, datesArray)
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* //=> 1
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*/
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export function closestIndexTo(dateToCompare, dates) {
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const date = toDate(dateToCompare);
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if (isNaN(Number(date))) return NaN;
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const timeToCompare = date.getTime();
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let result;
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let minDistance;
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dates.forEach(function (dirtyDate, index) {
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const currentDate = toDate(dirtyDate);
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if (isNaN(Number(currentDate))) {
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result = NaN;
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minDistance = NaN;
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return;
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}
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const distance = Math.abs(timeToCompare - currentDate.getTime());
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if (result == null || distance < minDistance) {
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result = index;
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minDistance = distance;
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}
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});
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return result;
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}
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// Fallback for modularized imports:
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export default closestIndexTo;
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