// Version: Feb 2020
//
// The following TypeScript program illustrates how easy it is to apply NexCalendar:
//
// Since software stores dates by its ordinal days from a special date,
// it is easy to convert any Gregorian date to NexCalendar date.
//
interface MonthDay {
month: number;
day: number;
}
interface WeekDate {
week: number;
weekday: number;
}
interface WeekdayName {
longName: string;
shortName: string;
}
class NexCalendar {
// Weekday = Day of the Week (1 = Monday ... 7 = Sunday, 8 = Sunday)
// Yearday = Ordinal Day of the Year (1 ... 365, 366 = Leap Sunday)
static get maxDaysInYear() { return 366 } // 366 is equal to the Leap Sunday
static get daysByWeek35() { return (35 * 7 + 1) } // Week 35 is the annual long week with 8 days
static get daysInMonths() { return [0, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31] }
static get daysByMonths() { return [0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366] }
static invalidInt(x: number, max: number) : boolean {
if (Number.isInteger(x) && Number.isInteger(max)) return (x < 1 || x > max);
else return true;
}
static getYeardayFromMonthDay(month: number, day: number) : number // month = 1 to 12, day = 1 to 31
{
if (this.invalidInt(month, 12) || this.invalidInt(day, this.daysInMonths[month])) return 0;
return (this.daysByMonths[month - 1] + day);
}
static getMonthDay(yearday: number) : MonthDay
{
if (this.invalidInt(yearday, this.maxDaysInYear)) return {month: 0, day: 0};
var month = 2;
if (yearday > this.daysByMonths[4]) month = 6;
if (yearday > this.daysByMonths[8]) month = 10;
if (yearday > this.daysByMonths[month]) month++; else month--;
if (yearday > this.daysByMonths[month]) month++;
var day = yearday - this.daysByMonths[month - 1];
return { month, day };
}
// week = 1 to 52, weekday = 1 to 7 or 8 for week 35 or 52.
static getYeardayFromWeekDate(week: number, weekday: number) : number
{
if (week === 35 && weekday === 8) return this.daysByWeek35;
if (week === 52 && weekday === 8) return this.maxDaysInYear;
if (this.invalidInt(week, 52) || this.invalidInt(weekday, 7)) return 0;
var yearday = (week - 1) * 7 + weekday;
if (week > 35) yearday++;
return yearday;
}
static getWeekDate(yearday: number) : WeekDate
{
if (this.invalidInt(yearday, this.maxDaysInYear)) return {week: 0, weekday: 0}; // Unknown
if (yearday === this.maxDaysInYear) return {week: 52, weekday: 8}; // The last week
if (yearday === this.daysByWeek35) return {week: 35, weekday: 8}; // The last week
if (yearday >= this.daysByWeek35) yearday--;
var week = (1 + Math.floor((yearday - 1) / 7));
var weekday = yearday - ((week - 1) * 7);
return { week, weekday };
}
static getWeekDateFromMonthDay(month: number, day: number) : WeekDate
{ return this.getWeekDate(this.getYeardayFromMonthDay(month, day));}
static getMonthDayFromWeekDate(week: number, weekday: number) : MonthDay
{ return this.getMonthDay(this.getYeardayFromWeekDate(week, weekday)); }
static getWeekdayName(week: number, weekday: number) : WeekdayName
{
if ((week === 35 || week === 52) && weekday === 8) weekday = 7; // Special Sunday
if (this.invalidInt(week, 52) || this.invalidInt(weekday, 7)) return {longName:"",shortName:""};
var date = new Date(2001,0,weekday) // 1 to 7 = Monday to Sunday
var longName = date.toLocaleString(undefined,{weekday:"long"});
var shortName = date.toLocaleString(undefined,{weekday:"short"});
return { longName, shortName };
}
static isLeapYear(year: number) : boolean
{
if( this.invalidInt(year,9999)) return false;
return ((year % 4 === 0) && (year % 100 !== 0) || (year % 400 === 0));
}
// year = 1 to 9999, month = 1 to 12, day = 1 to 31
static newDate(year: number, month: number = 1, day: number = 1,
hour: number = 0, minute: number = 0, second: number = 0, millisecond: number = 0)
: Date | undefined
{
if (!this.isLeapYear(year))
{
if (this.invalidInt(month, 12)) return undefined;
if (this.invalidInt(day, this.daysInMonths[month])) return undefined;
if (month === 12 && day === 31) { } // set the last day of the year
else if (month > 1 && day === this.daysInMonths[month]) { month++; day = 1; }
else if (month > 2) day++;
}
return new Date(year, month-1, day, hour, minute, second, millisecond);
}
// return the default Date String
static toString(date ?: Date) : string
{
if (date instanceof Date && !isNaN(Number(date))) {}
else return "";
var diff = 0;
var day = date.getDate();
var month = date.getMonth() + 1;
var year = date.getFullYear();
var yearbits = Number(date) - Number(new Date(date.getFullYear(), 0, 0));
var yearday = Math.floor(yearbits / (1000 * 60 * 60 * 24));
var weekDate = this.getWeekDate(yearday);
var wdayName = this.getWeekdayName(weekDate.week, weekDate.weekday);
if (!this.isLeapYear(year) && month > 2)
{ // the previous day
diff = -1; day--;
if (day === 0) day = this.daysInMonths[(month - 1)];
}
date.setDate(date.getDate() + diff);
var parts = date.toString().split(" ");
parts[0] = wdayName.shortName;
parts[2] = (day < 10 ? "0"+day : ""+day);
return parts.join(" ");
}
}
// Three extended functions are provided as DateTime extensions.
interface Date {
getNexDate(): MonthDay;
getNexWeekDate(): WeekDate;
getNexWeekdayName(): WeekdayName;
}
Date.prototype.getNexDate = function()
{
var year = this.getFullYear(); var month = this.getMonth()+1; var day = this.getDate();
if (NexCalendar.isLeapYear(year) || month < 3) return { year, month, day };
if (day === 1) return {year, month: month - 1, day: NexCalendar.daysInMonths[month - 1]};
else return {year: year, month: month, day: day - 1}; // month = 1 to 12
}
Date.prototype.getNexWeekDate = function()
{
var diff = Number(this) - Number(new Date(this.getFullYear(), 0, 0));
var yearday = Math.floor(diff / (1000 * 60 * 60 * 24));
var wkDate = NexCalendar.getWeekDate(yearday);
return {year: this.getFullYear(), week: wkDate.week, weekday: wkDate.weekday};
}
Date.prototype.getNexWeekdayName = function()
{
var diff = Number(this) - Number(new Date(this.getFullYear(), 0, 0));
var yearday = Math.floor(diff / (1000 * 60 * 60 * 24));
var wkDate = NexCalendar.getWeekDate(yearday);
return NexCalendar.getWeekdayName(wkDate.week, wkDate.weekday);
}
// e.g.
var date = NexCalendar.newDate(2021,2,29);
console.log(NexCalendar.toString(date));
var mthDay = (new Date()).getNexDate();
console.log("Month/day: " + mthDay.month + "/" + mthDay.day);
var wkDate = (new Date()).getNexWeekDate();
console.log("Week Date: W" + wkDate.week + "-" + wkDate.weekday);
var wkName = (new Date()).getNexWeekdayName();
console.log("Today is " + wkName.longName + " (" + wkName.shortName + ")");
console.log("Current Calendar: " + (new Date()).toString());
console.log("NexCalendar: " + NexCalendar.toString(new Date()));
// Copyright © 2020 Dr. Donny C.F. Lai & Justin J.S. Lai. All Rights Reserved.