Get Last Day of Persian Month + Solution

Question

after looking web, i cant find any function to do this, i have personal solution that is work. Maybe it will be useful for someone.

**using Moment Plugin to Convert date. ***moment(currentPersianDate).clone().endof('month').format('YYYY/MM/DD') => not Work in Persian Date

  function GetLastDayOfPersianMonth(calendar) {
            const currentDate = new Date();
            const currentPersianDate = moment(currentDate).locale('fa').format('YYYY/M/D');
            const splitDate = currentPersianDate.split("/");
            const year = splitDate[0];
            const month = splitDate[1];
            const lastDayOfPersianMonth = CalculateLeapYear(month, year);
    
            const endPersianMonth = year + "/" + month + "/" + lastDayOfPersianMonth;
        };

    function CalculateLeapYear(month, year) {
            if (month <= 6) {
                return 31;
            }
            if (month > 6 && month < 12) {
                return 30;
            }

            const leapMatch = [1, 5, 9, 13, 17, 22, 26, 30];
            const number = year % 33;
            const isLeap = leapMatch.includes(number);
           
            if (month == 12 && !isLeap) {
                return 29;
            }
            if (month == 12 && isLeap) {
                return 30;
            }
        }

user_14939090 · Answer

you can use this code in C# my site https://mohammadhosseinaref.ir

        public static string PersianDayOfWeek(DayOfWeek dayOfWeek)
    {
        switch (dayOfWeek)
        {
            case DayOfWeek.Sunday:
                return "یکشنبه";
            case DayOfWeek.Monday:
                return "دوشنبه";
            case DayOfWeek.Tuesday:
                return "سه شنبه";
            case DayOfWeek.Wednesday:
                return "چهار شنبه";
            case DayOfWeek.Thursday:
                return "پنج شنبه";
            case DayOfWeek.Friday:
                return "جمعه";
            case DayOfWeek.Saturday:
                return "شنبه";
            default:
                return null;
        }
    }

      public static Dictionary ListOfPersianDayOfMonth(int month, int years)
    {
        Dictionary dicDays = new Dictionary();

        PersianCalendar p = new PersianCalendar();

        var dates = Enumerable.Range(1, p.GetDaysInMonth(years, month))
               .Select(day => ParsePersianToGorgian(years + "/" + month + "/" + day))
               .ToList();

        foreach (var item in dates)
        {
            var day = GeorgianToPersian(item.Value, ShowMode.OnlyDate);
            dicDays.Add(int.Parse(day.Split('/')[2]), DayPersian(item.Value.DayOfWeek) + " " + day);
        }
        return dicDays;
    }

user_560376 · Answer

you can find one day before the first day of next month. for example, if you want to find the last day of the 6th month:

const firstDayOfNextMonth = moment.from('1400/07/01', 'fa', 'YYYY/MM/DD');
const lastDayOfMonth = firstDayOfNextMonth.add(-1,'d');
const lastDayOfMonthPersianDate = lastDayOfMonth.locale('fa').format('YYYY/M/D');

so for last day of current month:

const currentDate = new Date();
const currentPersianDate = moment(currentDate).locale('fa').add(1,'month');
const firstDayOfNextMonthSt = currentPersianDate.format('jYYYY') + '/' + currentPersianDate.format('jM') + '/01';
//and then
const firstDayOfNextMonth = moment.from(firstDayOfNextMonthSt, 'fa', 'YYYY/MM/DD');
const lastDayOfMonth = firstDayOfNextMonth.add(-1,'d');
const lastDayOfMonthPersianDate = lastDayOfMonth.locale('fa').format('YYYY/M/D');

you can write a function like this and use it:

function getLastDayOfMonthPersianDate(firstDayOfNextMonthSt){
    const firstDayOfNextMonth = moment.from(firstDayOfNextMonthSt, 'fa', 'YYYY/MM/DD');
    const lastDayOfMonth = firstDayOfNextMonth.add(-1,'d');
    const lastDayOfMonthPersianDate = lastDayOfMonth.locale('fa').format('YYYY/M/D');

    return lastDayOfMonthPersianDate;
}

see snippet for function usage:

function getLastDayOfMonthPersianDate(firstDayOfNextMonthSt){
    const firstDayOfNextMonth = moment.from(firstDayOfNextMonthSt, 'fa', 'YYYY/MM/DD');
    const lastDayOfMonth = firstDayOfNextMonth.add(-1,'d');
    const lastDayOfMonthPersianDate = lastDayOfMonth.locale('fa').format('YYYY/M/D');
    
    return lastDayOfMonthPersianDate;
}

const lastDayOfMonthPersianDate = getLastDayOfMonthPersianDate('1400/07/01');
console.log('last day of the 6th month');
console.log(lastDayOfMonthPersianDate);
console.log('-------');

const currentDate = new Date();
const currentPersianDate = moment(currentDate).locale('fa').add(1,'month');
const firstDayOfNextMonthSt = currentPersianDate.format('jYYYY') + '/' + currentPersianDate.format('jM') + '/01';
const lastDayOfCurrentMonthPersianDate = getLastDayOfMonthPersianDate(firstDayOfNextMonthSt);
console.log('last day of the current month');
console.log(lastDayOfCurrentMonthPersianDate);

user_11606728 · Answer

Here is an alternative solution without using libraries.

Given a Gregorian Date, the function will return the information about the Persian Month in that Gregorian Date.

The information returned is:

[1] The Persian Day (Number) (1-31) for that date

[2] The Persian Month (String)

[3] The Persian Year (Number)

[4] Total Days in the Persian Month (Number)

[5] The Gregorian Date that the Persian Month starts on (Date object)

[6] The Gregorian Date that the Persian Month ends on (Date object)

/*********************************************************************
* @function      : getPersianMonthInfo(date)
* @purpose       : Returns information on a Persian Month for a given Gregorian Date
* @version       : 1.00
* @author        : Mohsen Alyafei
* @date          : 07 Mar 2022
* @Licence       : MIT
* @param         : {date} a valid Gregorian Date Object
* @returns       : An Array of seven (7) elements with the following data:
*                  [0] The Gregorian Date (the input date) in YYYY-MM-DD format
*                  [1] The Persian Day (Number) for that date
*                  [2] The Persian Month (String)
*                  [3] The Persian Year (Number)
*                  [4] Total Days in the Persian Month (Number)
*                  [5] The Gregorian Date that the Persian Month starts on (Date object)
*                  [6] The Gregorian Date that the Persian Month ends on   (Date object)
**********************************************************************/
function getPersianMonthInfo(date) {
let sD=new Date(date),c='en-u-ca-persian-nu-latn',d=sD,gD=0,tD= 0,pD,n='numeric',
    iDay  =new Intl.DateTimeFormat(c,{day:n}).format(sD),
    iMonth=new Intl.DateTimeFormat(c,{month:'long'}).format(sD),
    iYear =new Intl.DateTimeFormat(c,{year:n}).format(sD).split(" ")[0];
for (let i=0;i<32;i++) {
    pD= new Intl.DateTimeFormat(c,{day:n}).format(d);
    if (+pD>tD) tD=pD,gD++; else break;
    d=new Date(d.setUTCDate(d.getUTCDate()+1));
    }
let gEndT=new Date(sD.setUTCDate(sD.getUTCDate()+gD-2));
return [new Date(date).toISOString().split("T")[0],+iDay,iMonth,+iYear,tD,new Date(gEndT.setUTCDate(gEndT.getUTCDate()-tD+1)),new Date(gEndT)];
}
//==================================================================















//==================================================================
// Test Cases
//==================================================================
output(getPersianMonthInfo(new Date(Date.now()))); // today's date
output(getPersianMonthInfo("2022-04-10"));         // 10 April 2022
//==================================================================


function output([gDate, iDay, iMonth, iYear, tD, gStart, gEnd]) {

console.log(`
Gregorian Date              : ${gDate}
Persian Day                 : ${iDay}
Persian Month               : ${iMonth}
Persian Year                : ${iYear}
Total Days in Persian Month : ${tD}
Persian Month Starts on     : ${gStart}
Persian Month Ends on       : ${gEnd}
`
);
}
//==================