Skip to content


Switch branches/tags

Name already in use

A tag already exists with the provided branch name. Many Git commands accept both tag and branch names, so creating this branch may cause unexpected behavior. Are you sure you want to create this branch?

Latest commit


Git stats


Failed to load latest commit information.
Latest commit message
Commit time

This project is at an alpha stage.

Things will break, and APIs might change. Be cautious using this in production. Additionally, not all methods have been tested for accuracy.


Kosher Zmanim is a TS/JS port of the KosherJava library.



npm install kosher-zmanim

UMD (browser):

<script src=""></script>

It is highly recommended that you pin the version (e.g., so updates don't break your app.

Usage and Documentation


ES6 modules / Typescript:

import * as KosherZmanim from "kosher-zmanim";


import { ComplexZmanimCalendar, getZmanimJson } from "kosher-zmanim";

CommonJS modules:

const KosherZmanim = require("kosher-zmanim");


const { ComplexZmanimCalendar, getZmanimJson } = require("kosher-zmanim");

UMD (browser):

For UMD, a global KosherZmanim object is exposed.

Library Usage:

The KosherJava library has been ported to JS, following the original API as close as possible. The classes are exposed as named exports. You can instantiate or extend those classes as necessary, the same way you would in Java.

const zmanimCalendar = new KosherZmanim.ZmanimCalendar();

See the KosherJava API documentation for more details.

Simple usage

Alternatively, there is a getZmanimJson() utility method.

const zmanim = KosherZmanim.getZmanimJson(options);

Check out the demo, and look at the code to see an example of how it's used.

options object

The options object has the following structure and defaults:

    date: Date | string | number = new Date(),
    timeZoneId: string
    locationName?: string,
    latitude: number,
    longitude: number,
    elevation?: number = 0,
    complexZmanim?: boolean = false,

Note about how zmanim are calculated

This library uses Luxon as a date/time library, since Javascript's Date object does not support setting timezones other than the system timezone. All class methods that return a DateTime object will be in UTC.

Breaking changes from KosherJava

  • AstronomicalCalendar.getTemporalHour() returns null instead of Long.MIN_VALUE if the calculations cannot be completed.
  • JS/TS does not have a parallel to Java's Long.MIN_VALUE, so Long_MIN_VALUE is set to NaN.
  • The following methods are not supported:
    • AstronomicalCalendar.toString()
    • AstronomicalCalendar.toJSON() (Use ZmanimFormatter.toJSON(astronomicalCalendar) instead).
    • AstronomicalCalculator.getDefault() (Use new NOAACalculator() instead).
    • JewishCalendar.getDafYomiBavli() (Use YomiCalculator.getDafYomiBavli(jewishCalendar) instead).
    • JewishCalendar.getDafYomiYerushalmi() (Use YerushalmiYomiCalculator.getDafYomiYerushalmi(jewishCalendar) instead).
    • Time.toString() (Use new ZmanimFormatter(TimeZone.getTimeZone("UTC")).format(time) instead).
    • ZmanimFormatter.toXML()
  • Some method signatures are different, due to the differences between Java and JS.
  • The Zman class uses public members instead of getters and setters.