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49 lines
1.5 KiB
49 lines
1.5 KiB
var parse = require('../parse/index.js') |
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/** |
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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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* @param {Date|String|Number} dateToCompare - the date to compare with |
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* @param {Date[]|String[]|Number[]} datesArray - the array to search |
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* @returns {Number} an index of the date closest to the given date |
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* @throws {TypeError} the second argument must be an instance of Array |
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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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* var dateToCompare = new Date(2015, 8, 6) |
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* var 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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* var result = closestIndexTo(dateToCompare, datesArray) |
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* //=> 1 |
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*/ |
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function closestIndexTo (dirtyDateToCompare, dirtyDatesArray) { |
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if (!(dirtyDatesArray instanceof Array)) { |
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throw new TypeError(toString.call(dirtyDatesArray) + ' is not an instance of Array') |
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} |
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var dateToCompare = parse(dirtyDateToCompare) |
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var timeToCompare = dateToCompare.getTime() |
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var result |
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var minDistance |
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dirtyDatesArray.forEach(function (dirtyDate, index) { |
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var currentDate = parse(dirtyDate) |
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var distance = Math.abs(timeToCompare - currentDate.getTime()) |
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if (result === undefined || 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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module.exports = closestIndexTo
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