javascript - Date formula, Calculating Leap Year, Week, etc, in Persian Datetime -

old title: how calculate number of week in given month

due answer provide change title...

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i'm creating library wrap in project, provide date information in culture,

the library this:

///<reference path="idate.ts"/> /**  * created hassan on 1/28/2016.  */ // references: // 1- http://www.aftabir.com/encyclopedia/urgent/calendar/chronometry/leapyear_new.php var persiandate = (function () {     function persiandate(year, month, day, firstdayofweek) {         this.day = day;         this.month = month;         this.year = year;         this.firstdayofweek = firstdayofweek;     }     persiandate.prototype.isleapyear = function () {         var year = this.year;         //var = 0.025;         //var b = 266;         //var leapdays0;         //var leapdays1;         //var frac0;         //var frac1;         //if (year > 0) {         //    leapdays0 = ((year + 38) % 2820) * 0.24219 + a; // 0.24219 ~ days of 1 year         //    leapdays1 = ((year + 39) % 2820) * 0.24219 + a; // 38 days difference of epoch 2820-year cycle         //}         //else if (year < 0) {         //    leapdays0 = ((year + 39) % 2820) * 0.24219 + a;         //    leapdays1 = ((year + 40) % 2820) * 0.24219 + a;         //}         //else {         //    return false;         //}         //frac0 = math.floor((leapdays0 - math.floor(leapdays0)) * 1000);         //frac1 = math.floor((leapdays1 - math.floor(leapdays1)) * 1000);         //if (frac0 <= b && frac1 > b)         //    return true;         //else         //    return false;          var = year+2346;         var a2 = year-1 + 2346; //(a-1)=n-1+2346 -> 'a-1' name of last year         var b1 = math.ceil(a * 365.24219879);         var b2 = math.ceil(a2 * 365.24219879);          return b1 - b2 == 366;     };     persiandate.prototype.getdaysinmonth = function () {         switch (this.month) {             case 1:             case 2:             case 3:             case 4:             case 5:             case 6:                 return 31;             case 7:             case 8:             case 9:             case 10:             case 11:                 return 30;             case 12:                 return (this.isleapyear() ? 30 : 29);         }         return undefined;     };     persiandate.prototype.getdaysinweek = function () {         return 7;     };     persiandate.prototype.getdaysinyear = function () {         return 365 + (this.isleapyear() ? 1 : 0);     };     persiandate.prototype.getmonthsinyear = function () {         return 12;     };     persiandate.prototype.getweeksinyear = function () {         return this.getdaysinyear() + (this.getweekfirstday()) / 7;     };     persiandate.prototype.getweeksinmonth = function () {         var month = this.getmonth();         console.log(month);         var totaldaystomonthstart;         if (month <= 7) {             totaldaystomonthstart = (month - 1) * 31;             console.log(totaldaystomonthstart)         }         else {             totaldaystomonthstart = 186 + ((month - 6 - 1) * 30);             console.log(totaldaystomonthstart)         }         var remaineddaywithoutstartingdays = 7 - (totaldaystomonthstart% 7);          var weeksafterstarting = math.floor((this.getdaysinmonth() - remaineddaywithoutstartingdays) / 7);          console.log("remaineddaywithoutstartingdays: ", remaineddaywithoutstartingdays);         console.log("weeksafterstarting: ", weeksafterstarting)         return weeksafterstarting + (remaineddaywithoutstartingdays != 0)? 1:0;     };     persiandate.prototype.getweekfirstday = function () {         var n = this.year;         var = n - 1;         var b = + 2346;         var yearlength = b * 365.24219879; //tool sal motevasete khorshidi         var c = math.ceil(yearlength);         //نظر به آنکه مبداء سال ۲۳۴۶- روز سه‌شنبه بوده است (و با انتساب اعداد صفر و يک تا شش به شنبه و يکشنبه تا جمعه) به c سه واحد مى‌افزائيم يا از آن چهار واحد کم مى‌کنيم تا به مبداء شنبه انتقال يابيم و عدد حاصل را d مى‌ناميم.         var d = c + 3;         var r = d % 7;         console.log("first day of year: " + r);         return r;     };     persiandate.prototype.getday = function () {         return this.day;     };     persiandate.prototype.getweekofyear = function () {         console.log("week of year: " + this.getdayofyear() + this.getweekfirstday() / 7);         return this.getdayofyear() + this.getweekfirstday() / 7;     };     persiandate.prototype.getweekofmonth = function () {         return undefined;     };     persiandate.prototype.getdayofweek = function () {         return undefined;     };     persiandate.prototype.getdayofmonth = function () {         return undefined;     };     persiandate.prototype.getdayofyear = function () {         return undefined;     };     persiandate.prototype.getmonth = function () {         return this.month;     };     persiandate.prototype.getyear = function () {         return this.year;     };     return persiandate; })(); //# sourcemappingurl=persiandate.js.map  var pd = new persiandate(1395, 1, 1); pd.getweekfirstday(); pd.getweeksinmonth(); 

first day of week return 0 6 (i'm not sure if standard datetime or not)

and thing become problematic getweeksinmonth:

first made work, in month full set of days in first weeks failed, change it, doesn't work @ all. searched , couldn't right formula. (better didn't got formula @ all)

what should return weeks in given month:

for given date 1395/01 should image:

as can see in fifth , eleven month have 6 week in 1 month, , other 5days. hopw fix it? kinda have issue weeks in kinda dates :'(

thank you.

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note: guys in future may visit thread, class based on persiancalendar, not gregoriancalendar.

it sure take lot time since helped me solve issue, , forgot all, made repository, important formula there:

https://github.com/deadmann/calendar