DateDayDifference.js

/*
 DateDayDifference Method
 ------------------------
 DateDayDifference method calculates the number of days between two dates.

 Algorithm & Explanation : https://ncalculators.com/time-date/date-difference-calculator.htm
*/

import { isLeapYear } from '../Maths/LeapYear'
import { parseDate } from '../Timing-Functions/ParseDate'

const DateToDay = (dd, mm, yyyy) => {
 return (
 365 * (yyyy - 1) +
 Math.floor((yyyy - 1) / 4) -
 Math.floor((yyyy - 1) / 100) +
 Math.floor((yyyy - 1) / 400) +
 dd +
 Math.floor((367 * mm - 362) / 12) +
 (mm <= 2 ? 0 : isLeapYear(yyyy) ? -1 : -2)
 )
}

const DateDayDifference = (date1, date2) => {
 const firstDate = parseDate(date1)
 const secondDate = parseDate(date2)

 return Math.abs(
 DateToDay(secondDate.day, secondDate.month, secondDate.year) -
 DateToDay(firstDate.day, firstDate.month, firstDate.year)
 )
}

// Example : DateDayDifference('17/08/2002', '10/10/2020') => 6630

export { DateDayDifference }