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index.js
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index.js
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import toDate from '../toDate/index.ts'
import requiredArgs from '../_lib/requiredArgs/index.ts'
/**
* @name closestIndexTo
* @category Common Helpers
* @summary Return an index of the closest date from the array comparing to the given date.
*
* @description
* Return an index of the closest date from the array comparing to the given date.
*
* ### v2.0.0 breaking changes:
*
* - [Changes that are common for the whole library](https://github.com/date-fns/date-fns/blob/master/docs/upgradeGuide.md#Common-Changes).
*
* - Now, `closestIndexTo` doesn't throw an exception
* when the second argument is not an array, and returns Invalid Date instead.
*
* @param {Date|Number} dateToCompare - the date to compare with
* @param {Date[]|Number[]} datesArray - the array to search
* @returns {Number} an index of the date closest to the given date
* @throws {TypeError} 2 arguments required
*
* @example
* // Which date is closer to 6 September 2015?
* var dateToCompare = new Date(2015, 8, 6)
* var datesArray = [
* new Date(2015, 0, 1),
* new Date(2016, 0, 1),
* new Date(2017, 0, 1)
* ]
* var result = closestIndexTo(dateToCompare, datesArray)
* //=> 1
*/
export default function closestIndexTo(dirtyDateToCompare, dirtyDatesArray) {
requiredArgs(2, arguments)
var dateToCompare = toDate(dirtyDateToCompare)
if (isNaN(dateToCompare)) {
return NaN
}
var timeToCompare = dateToCompare.getTime()
var datesArray
// `dirtyDatesArray` is undefined or null
if (dirtyDatesArray == null) {
datesArray = []
// `dirtyDatesArray` is Array, Set or Map, or object with custom `forEach` method
} else if (typeof dirtyDatesArray.forEach === 'function') {
datesArray = dirtyDatesArray
// If `dirtyDatesArray` is Array-like Object, convert to Array. Otherwise, make it empty Array
} else {
datesArray = Array.prototype.slice.call(dirtyDatesArray)
}
var result
var minDistance
datesArray.forEach(function(dirtyDate, index) {
var currentDate = toDate(dirtyDate)
if (isNaN(currentDate)) {
result = NaN
minDistance = NaN
return
}
var distance = Math.abs(timeToCompare - currentDate.getTime())
if (result == null || distance < minDistance) {
result = index
minDistance = distance
}
})
return result
}