@hebcal/hdate
converts between Hebrew and Gregorian dates
Installation
$ npm install @hebcal/hdateSynopsis
import {greg, abs2hebrew} from '@hebcal/hdate';
const date = new Date(2008, 10, 13); // 13 November 2008
const abs = greg.greg2abs(date);
const hdate = abs2hebrew(abs); // {yy: 5769, mm: CHESHVAN, dd: 15}Members
- greg
-
Gregorian date helper functions.
Functions
-
hebrew2abs(year, month, day) ⇒
number -
Converts Hebrew date to R.D. (Rata Die) fixed days. R.D. 1 is the imaginary date Monday, January 1, 1 on the Gregorian Calendar.
-
abs2hebrew(abs) ⇒
SimpleHebrewDate -
Converts absolute R.D. days to Hebrew date
-
isLeapYear(year) ⇒
boolean -
Returns true if Hebrew year is a leap year
-
monthsInYear(year) ⇒
number -
Number of months in this Hebrew year (either 12 or 13 depending on leap year)
-
daysInMonth(month, year) ⇒
number -
Number of days in Hebrew month in a given year (29 or 30)
- getMonthName(month, year)
-
Returns a transliterated string name of Hebrew month in year, for example 'Elul' or 'Cheshvan'.
-
elapsedDays(year) ⇒
number -
Days from sunday prior to start of Hebrew calendar to mean conjunction of Tishrei in Hebrew YEAR
-
daysInYear(year) ⇒
number -
Number of days in the hebrew YEAR. A common Hebrew calendar year can have a length of 353, 354 or 355 days A leap Hebrew calendar year can have a length of 383, 384 or 385 days
-
longCheshvan(year) ⇒
boolean -
true if Cheshvan is long in Hebrew year
-
shortKislev(year) ⇒
boolean -
true if Kislev is short in Hebrew year
-
monthFromName(monthName) ⇒
number -
Converts Hebrew month string name to numeric
-
getYahrzeit(hyear, date) ⇒
Date -
Calculates yahrzeit.
hyearmust be after originaldateof death. Returnsundefinedwhen requested year preceeds or is same as original year.Hebcal uses the algorithm defined in "Calendrical Calculations" by Edward M. Reingold and Nachum Dershowitz.
The customary anniversary date of a death is more complicated and depends also on the character of the year in which the first anniversary occurs. There are several cases:
- If the date of death is Marcheshvan 30, the anniversary in general depends on the first anniversary; if that first anniversary was not Marcheshvan 30, use the day before Kislev 1.
- If the date of death is Kislev 30, the anniversary in general again depends on the first anniversary — if that was not Kislev 30, use the day before Tevet 1.
- If the date of death is Adar II, the anniversary is the same day in the last month of the Hebrew year (Adar or Adar II).
- If the date of death is Adar I 30, the anniversary in a Hebrew year that is not a leap year (in which Adar only has 29 days) is the last day in Shevat.
- In all other cases, use the normal (that is, same month number) anniversary of the date of death. [Calendrical Calculations p. 113]
-
getBirthdayOrAnniversary(hyear, date) ⇒
Date -
Calculates a birthday or anniversary (non-yahrzeit).
hyearmust be after originaldateof anniversary. Returnsundefinedwhen requested year preceeds or is same as original year.Hebcal uses the algorithm defined in "Calendrical Calculations" by Edward M. Reingold and Nachum Dershowitz.
The birthday of someone born in Adar of an ordinary year or Adar II of a leap year is also always in the last month of the year, be that Adar or Adar II. The birthday in an ordinary year of someone born during the first 29 days of Adar I in a leap year is on the corresponding day of Adar; in a leap year, the birthday occurs in Adar I, as expected.
Someone born on the thirtieth day of Marcheshvan, Kislev, or Adar I has his birthday postponed until the first of the following month in years where that day does not occur. [Calendrical Calculations p. 111]
-
gematriya(num) ⇒
string -
Converts a numerical value to a string of Hebrew letters.
When specifying years of the Hebrew calendar in the present millennium, we omit the thousands (which is presently 5 [ה]).
-
gematriyaStrToNum(str) ⇒
number -
Converts a string of Hebrew letters to a numerical value.
Only considers the value of Hebrew letters
אthroughת. Ignores final Hebrew letters such asך(kaf sofit) orם(mem sofit) and vowels (nekudot).
greg
Gregorian date helper functions.
months : enum
Hebrew months of the year (NISAN=1, TISHREI=7)
Kind: global enum
Read only: true
Properties
| Name | Type | Default | Description |
|---|---|---|---|
| NISAN | number |
1 |
Nissan / ניסן |
| IYYAR | number |
2 |
Iyyar / אייר |
| SIVAN | number |
3 |
Sivan / סיון |
| TAMUZ | number |
4 |
Tamuz (sometimes Tammuz) / תמוז |
| AV | number |
5 |
Av / אב |
| ELUL | number |
6 |
Elul / אלול |
| TISHREI | number |
7 |
Tishrei / תִּשְׁרֵי |
| CHESHVAN | number |
8 |
Cheshvan / חשון |
| KISLEV | number |
9 |
Kislev / כסלו |
| TEVET | number |
10 |
Tevet / טבת |
| SHVAT | number |
11 |
Sh'vat / שבט |
| ADAR_I | number |
12 |
Adar or Adar Rishon / אדר |
| ADAR_II | number |
13 |
Adar Sheini (only on leap years) / אדר ב׳ |
hebrew2abs(year, month, day) ⇒ number
Converts Hebrew date to R.D. (Rata Die) fixed days. R.D. 1 is the imaginary date Monday, January 1, 1 on the Gregorian Calendar.
Kind: global function
| Param | Type | Description |
|---|---|---|
| year | number |
Hebrew year |
| month | number |
Hebrew month |
| day | number |
Hebrew date (1-30) |
abs2hebrew(abs) ⇒ SimpleHebrewDate
Converts absolute R.D. days to Hebrew date
Kind: global function
| Param | Type | Description |
|---|---|---|
| abs | number |
absolute R.D. days |
isLeapYear(year) ⇒ boolean
Returns true if Hebrew year is a leap year
Kind: global function
| Param | Type | Description |
|---|---|---|
| year | number |
Hebrew year |
monthsInYear(year) ⇒ number
Number of months in this Hebrew year (either 12 or 13 depending on leap year)
Kind: global function
| Param | Type | Description |
|---|---|---|
| year | number |
Hebrew year |
daysInMonth(month, year) ⇒ number
Number of days in Hebrew month in a given year (29 or 30)
Kind: global function
| Param | Type | Description |
|---|---|---|
| month | number |
Hebrew month (e.g. months.TISHREI) |
| year | number |
Hebrew year |
getMonthName(month, year)
Returns a transliterated string name of Hebrew month in year, for example 'Elul' or 'Cheshvan'.
Kind: global function
| Param | Type | Description |
|---|---|---|
| month | number |
Hebrew month (e.g. months.TISHREI) |
| year | number |
Hebrew year |
elapsedDays(year) ⇒ number
Days from sunday prior to start of Hebrew calendar to mean conjunction of Tishrei in Hebrew YEAR
Kind: global function
| Param | Type | Description |
|---|---|---|
| year | number |
Hebrew year |
daysInYear(year) ⇒ number
Number of days in the hebrew YEAR. A common Hebrew calendar year can have a length of 353, 354 or 355 days A leap Hebrew calendar year can have a length of 383, 384 or 385 days
Kind: global function
| Param | Type | Description |
|---|---|---|
| year | number |
Hebrew year |
longCheshvan(year) ⇒ boolean
true if Cheshvan is long in Hebrew year
Kind: global function
| Param | Type | Description |
|---|---|---|
| year | number |
Hebrew year |
shortKislev(year) ⇒ boolean
true if Kislev is short in Hebrew year
Kind: global function
| Param | Type | Description |
|---|---|---|
| year | number |
Hebrew year |
monthFromName(monthName) ⇒ number
Converts Hebrew month string name to numeric
Kind: global function
| Param | Type | Description |
|---|---|---|
| monthName | string |
monthName |
getYahrzeit(hyear, date) ⇒ Date
Calculates yahrzeit.
hyear must be after original date of death.
Returns undefined when requested year preceeds or is same as original year.
Hebcal uses the algorithm defined in "Calendrical Calculations" by Edward M. Reingold and Nachum Dershowitz.
The customary anniversary date of a death is more complicated and depends also on the character of the year in which the first anniversary occurs. There are several cases:
- If the date of death is Marcheshvan 30, the anniversary in general depends on the first anniversary; if that first anniversary was not Marcheshvan 30, use the day before Kislev 1.
- If the date of death is Kislev 30, the anniversary in general again depends on the first anniversary — if that was not Kislev 30, use the day before Tevet 1.
- If the date of death is Adar II, the anniversary is the same day in the last month of the Hebrew year (Adar or Adar II).
- If the date of death is Adar I 30, the anniversary in a Hebrew year that is not a leap year (in which Adar only has 29 days) is the last day in Shevat.
- In all other cases, use the normal (that is, same month number) anniversary of the date of death. [Calendrical Calculations p. 113]
Kind: global function
Returns: Date - anniversary occurring in hyear
| Param | Type | Description |
|---|---|---|
| hyear | number |
Hebrew year |
| date |
Date | SimpleHebrewDate | number
|
Gregorian or Hebrew date of death |
Example
import {getYahrzeit} from '@hebcal/hdate';
const dt = new Date(2014, 2, 2); // '2014-03-02' == '30 Adar I 5774'
const anniversary = getYahrzeit(5780, dt); // '2/25/2020' == '30 Sh\'vat 5780'getBirthdayOrAnniversary(hyear, date) ⇒ Date
Calculates a birthday or anniversary (non-yahrzeit).
hyear must be after original date of anniversary.
Returns undefined when requested year preceeds or is same as original year.
Hebcal uses the algorithm defined in "Calendrical Calculations" by Edward M. Reingold and Nachum Dershowitz.
The birthday of someone born in Adar of an ordinary year or Adar II of a leap year is also always in the last month of the year, be that Adar or Adar II. The birthday in an ordinary year of someone born during the first 29 days of Adar I in a leap year is on the corresponding day of Adar; in a leap year, the birthday occurs in Adar I, as expected.
Someone born on the thirtieth day of Marcheshvan, Kislev, or Adar I has his birthday postponed until the first of the following month in years where that day does not occur. [Calendrical Calculations p. 111]
Kind: global function
Returns: Date - anniversary occurring in hyear
| Param | Type | Description |
|---|---|---|
| hyear | number |
Hebrew year |
| date |
Date | SimpleHebrewDate | number
|
Gregorian or Hebrew date of event |
Example
import {getBirthdayOrAnniversary} from '@hebcal/hdate';
const dt = new Date(2014, 2, 2); // '2014-03-02' == '30 Adar I 5774'
const anniversary = getBirthdayOrAnniversary(5780, dt); // '3/26/2020' == '1 Nisan 5780'gematriya(num) ⇒ string
Converts a numerical value to a string of Hebrew letters.
When specifying years of the Hebrew calendar in the present millennium, we omit the thousands (which is presently 5 [ה]).
Kind: global function
| Param | Type |
|---|---|
| num | number |
Example
gematriya(5774) // 'תשע״ד' - cropped to 774
gematriya(25) // 'כ״ה'
gematriya(60) // 'ס׳'
gematriya(3761) // 'ג׳תשס״א'
gematriya(1123) // 'א׳קכ״ג'gematriyaStrToNum(str) ⇒ number
Converts a string of Hebrew letters to a numerical value.
Only considers the value of Hebrew letters א through ת.
Ignores final Hebrew letters such as ך (kaf sofit) or ם (mem sofit)
and vowels (nekudot).
Kind: global function
| Param | Type |
|---|---|
| str | string |