kdate.js

/* kdate.js - Kaluach Javascript Hebrew date routines
 *   Version 1.00
 * Copyright (C) 5760,5761 (2000 CE), by Abu Mami and Yisrael Hersch.
 *   All Rights Reserved.
 *   All copyright notices in this script must be left intact.
 * Based on the formula by Gauss
 * Terms of use:
 *   - Permission will be granted to use this script on personal
 *     web pages. All that's required is that you please ask.
 *     (Of course if you want to send a few dollars, that's OK too :-)
 *   - Use on commercial web sites requires a $50 payment.
 * website: http://www.kaluach.net
 * email: abumami@kaluach.net
 */

function makeArray() {
  this[0] = makeArray.arguments.length;
  for (i = 0; i < makeArray.arguments.length; i = i + 1)
    this[i+1] = makeArray.arguments[i];
}

var hebMonth = new makeArray(
  'Nisan', 'Iyyar', 'Sivan', 'Tammuz', 'Av', 'Elul',
  'Tishrei', 'Cheshvan', 'Kislev', 'Tevet', 'Shevat',
  'Adar', 'Adar I', 'Adar II');

var civMonth = new makeArray(
  'January', 'February', 'March', 'April', 'May', 'June',
  'July', 'August', 'September', 'October', 'November', 'December');

var weekDay = new makeArray(
  'S', 'M', 'T', 'W', 'Th', 'F', 'Sh');

function Gauss(year) {
  var a,b,c;
  var m;
  var	Mar;	// "day in March" on which Pesach falls (return value)

  a = Math.floor((12 * year + 17) % 19);
  b = Math.floor(year % 4);
  m = 32.044093161144 + 1.5542417966212 * a +  b / 4.0 - 0.0031777940220923 * year;
  if (m < 0)
    m -= 1;
  Mar = Math.floor(m);
  if (m < 0)
    m++;
  m -= Mar;

  c = Math.floor((Mar + 3 * year + 5 * b + 5) % 7);
  if(c == 0 && a > 11 && m >= 0.89772376543210 )
    Mar++;
  else if(c == 1 && a > 6 && m >= 0.63287037037037)
    Mar += 2;
  else if(c == 2 || c == 4 || c == 6)
    Mar++;

  Mar += Math.floor((year - 3760) / 100) - Math.floor((year - 3760) / 400) - 2;
  return Mar;
}

function leap(y) {
  return ((y % 400 == 0) || (y % 100 != 0 && y % 4 == 0));
}

function civMonthLength(month, year) {
  if(month == 2)
    return 28 + leap(year);
  else if(month == 4 || month == 6 || month == 9 || month == 11)
    return 30;
  else
    return 31;
}

function civ2heb(day, month, year) {
  var d = day;
  var	m = month;
  var y = year;
  var hy;
  var pesach;
  var anchor;
  var adarType;

  m -= 2;
  if (m <= 0) { // Jan or Feb
    m += 12;
    y -= 1;
  }

  d += Math.floor(7 * m / 12 + 30 * (m - 1)); // day in March
  hy = y + 3760;	// get Hebrew year
  pesach = Gauss(hy);
  if (d <= pesach - 15) { // before 1 Nisan
    anchor = pesach;
    d += 365;
    if(leap(y))
      d++;
    y -= 1;
    hy -= 1;
    pesach = Gauss(hy);
  }
  else
    anchor = Gauss(hy + 1);

  d -= pesach - 15;
  anchor -= pesach - 12;
  y++;
  if(leap(y))
    anchor++;

  for(m = 0; m < 11; m++) {
    var days;
    if(m == 7 && anchor % 30 == 2)
      days = 30; // Cheshvan
    else if(m == 8 && anchor % 30 == 0)
      days = 29; // Kislev
    else
      days = 30 - m % 2;
    if(d <= days)
      break;
    d -= days;
  }

  adarType = 0;			// plain old Adar
  if (m == 11 && anchor >= 30) {
    if (d > 30) {
      adarType = 2;	// Adar 2
      d -= 30;
    }
    else
      adarType = 1;	// Adar 1
  }

  if(m >= 6)		// Tishrei or after?
    hy++;		// then bump up year

  if(m == 11)			// Adar?
    m += adarType;	// adjust for Adars

  return (d + ' ' + m + ' ' + hy);
}


function Easter(Y) {
  // based on the algorithm of Oudin
  var C = Math.floor(Y / 100);
  var N = Y - 19 * Math.floor(Y / 19);
  var K = Math.floor((C - 17) / 25);
  var I = C - Math.floor(C / 4) - Math.floor((C - K) / 3) + 19 * N + 15;
  I = I - 30*Math.floor((I / 30));
  I = I - Math.floor(I / 28) * (1 - Math.floor(I / 28) * Math.floor(29 / (I + 1)) * Math.floor((21 - N) / 11));
  var J = Y + Math.floor(Y / 4) + I + 2 - C + Math.floor(C / 4);
  J = J - 7 * Math.floor(J / 7);
  var L = I - J;
  var M = 3 + Math.floor((L + 40) / 44);
  var D = L + 28 - 31 * Math.floor(M / 4);

  var ret = new Object();
  ret[1] = M;
  ret[2] = D;
  return ret;
}

function DOW(day,month,year) {
  var a = Math.floor((14 - month)/12);
  var y = year - a;
  var m = month + 12*a - 2;
  var d = (day + y + Math.floor(y/4) - Math.floor(y/100) +
    Math.floor(y/400) + Math.floor((31*m)/12)) % 7;
  return d + 1;
}

function NthDOW(nth,weekday,month,year) {
  if (nth > 0)
    return (nth - 1) * 7 + 1 + (7 + weekday - DOW((nth - 1) * 7 + 1, month, year)) % 7;
  var days = civMonthLength(month, year);
  return days - (DOW(days, month, year) - weekday + 7) % 7;
}

function holidays(cday, cmonth, cyear) {
  // American civil holidays and some major religious holiday
  if (cmonth == 1 && cday == 1)
    return "New Year's Day";
  else if (cmonth == 2 && cday == 12)
    return "Lincoln's Birthday";
  else if (cmonth == 2 && cday == 14)
    return "Valentine's Day";
  else if (cmonth == 2 && cday == NthDOW(3, 2, 2, cyear))
    return "President's Day";
  else if (cmonth == 3 && cday == 17)
    return "St. Patrick's Day";
  else if (cmonth == 3 || cmonth == 4) {
    var e = Easter(cyear);
    if (cmonth == e[1] && cday == e[2])
      return "Easter";
  }
  else if (cmonth == 5 && cday == NthDOW(2, 1, 5, cyear))
    return "Mother's Day";
  else if (cmonth == 5 && cday == NthDOW(3, 7, 5, cyear))
    return "Armed Forces Day";
  else if (cmonth == 5 && cday == NthDOW(0, 2, 5, cyear))
    return "Memorial Day";
  else if (cmonth == 6 && cday == 14)
    return "Flag Day";
  else if (cmonth == 6 && cday == NthDOW(3, 1, 6, cyear))
    return "Father's Day";
  else if (cmonth == 7 && cday == 4)
    return "Independence Day";
  else if (cmonth == 9 && cday == NthDOW(1, 2, 9, cyear))
    return "Labor Day";
  else if (cmonth == 10 && cday == NthDOW(2, 2, 10, cyear))
    return "Columbus Day";
  else if (cmonth == 10 && cday == 31)
    return "Halloween";
  else if (cmonth == 11 && cday == 11)
    return "Veterans' Day";
  else if (cmonth == 11 && cday == NthDOW(4, 5, 11, cyear))
    return "Thanksgiving";
  else if (cmonth == 12 && cday == 25)
    return "Christmas";

  return "";
}

function moadim(cday, cmonth, cyear, hday, hmonth, dow) {
  if(hmonth == 6) {
    if(hday == 1 || hday == 2)
      return "Rosh Hashana"
    else if(hday == 3 && dow != 7)
      return "Fast of Gedalia";
    else if(hday == 4 && dow == 1)
      return "Fast of Gedalia";
    else if(hday == 10)
      return "Yom Kippur"
    else if(hday >= 15 && hday <= 22)
      return "Sukkot"
    else if(hday == 23)
      return "Sukkot (d)"
  }
  else if(hmonth == 8) {
    if(hday >= 25)
      return "Chanukkah"
  }
  else if(hmonth == 9) {
    if(hday <= 2) {
      return "Chanukkah"
    }
    else if(hday == 3) {
      // Kislev can be malei or chaser
      if(cday == 1) {
        cday = 29;
        cmonth = 11;
      }
      else if(cday == 2) {
        cday = 30;
        cmonth = 11;
      }
      else
        cday -= 3;
      var hdate = civ2heb(cday, cmonth, cyear);
      hd = eval(hdate.substring(0, hdate.indexOf(' ')));
      if(hd == 29)
        return "Chanukkah"
    }
    else if(hday == 10)
      return "Fast of Tevet"
  }
  else if(hmonth == 10) {
    if(hday==15)
      return "Tu b'Shvat"
  }
  else if(hmonth == 11 || hmonth == 13) {
    if(hday == 11 && dow == 5)
      return "Taanit Esther"
    else if(hday == 13 && dow != 7)
      return "Taanit Esther"
    else if(hday == 14)
      return "Purim"
    else if(hday == 15)
      return "Shushan Purim"
  }
  else if(hmonth == 0) {

    if(hday == 12 && dow == 5)
      return "Taanit Bechorot"
    else if(hday == 14 && dow != 7)
      return "Taanit Bechorot"
    else if(hday >= 15 && hday <= 21)
      return "Pesach"
    else if(hday == 22)
      return "Pesach (d)"
  }
  else if(hmonth == 1) {
    if(hday == 3 && dow == 5)
      return "Yom Ha'Atzmaut"
    else if(hday == 4 && dow == 5)
      return "Yom Ha'Atzmaut"
    else if(hday == 5 && dow != 6 && dow != 7)
      return "Yom Ha'Atzmaut"
    if(hday == 14)
      return "Pesah sheni"
    else if(hday == 18)
      return "Lag B'Omer"
    if(hday == 28)
      return "Yom Yerushalayim"
  }
  else if(hmonth == 2) {
    if(hday == 6)
      return "Shavuot"
    else if(hday == 7)
      return "Shavuot (d)"
  }
  else if(hmonth == 3) {
    if(hday == 17 && dow != 7)
      return "Fast of Tammuz"
    if(hday == 18 && dow == 1)
      return "Fast of Tammuz"
  }
  else if(hmonth == 4) {
    if(hday == 9 && dow != 7)
      return "Tisha B'Av"
    if(hday == 10 && dow == 1)
      return "Tisha B'Av"
    if(hday == 15)
      return "Tu B'Av"
  }

  return "";
}