Is There Tachanun? (Chabad)

A streamlined, responsive static web app designed to answer the daily question: "Do we say Tachanun today?" This tool follows the fixed, date-based omission schedule according to Chabad-Lubavitch custom.

Disclaimer: This app is a tool to assist with the schedule and should not replace a Luach or a Rav for final halachic rulings.

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🚀 Features

• Today at a Glance: Instant "Yes/No" answer for the current date.
• Hebrew Calendar Integration: Runs entirely in the browser using the Hebrew calendar (no server-side API; a zmanim library is loaded from a CDN only when GPS is allowed).
• Smart Date Picker: Look up any past or future date to check its status.
• Rule Transparency: Displays the specific halachic rule or occasion triggered for that date.
• Mincha Awareness: Includes a "Mincha Eve" note to remind users when Tachanun is omitted the afternoon prior.
• Modern UI: A clean, responsive design with automatic Light/Dark mode support.
• URL Mobile Override: Open /?mobile=1 (or /mobile) to force the compact mobile layout on any device.
• URL Kiosk Override: Open /?kiosk=1 (or /kiosk) for a fixed 1080x1920 portrait kiosk layout with title, Shacharis/Mincha status, and the current secular/Hebrew date display (without the date selector).
• Traffic Visibility: Open /visits to view the running total site visit count.

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📜 Halachic Logic & Sources

The app’s logic is based on the fixed-date omissions published by:

• Chabad.org
• Shulchanaruchharav.com

Important Scope Note

Please Note: This app tracks fixed-date omissions (e.g., Rosh Chodesh, the month of Nissan, specific Chassidic holidays).

This schedule does not include Eretz Yisroel specific dates or Daati Le'umi dates like Yom Ha'atzmaut, alternate Chagim dates, etc.

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📖 How it Works

The application calculates the current Hebrew date and cross-references it against a database of Chabad customs.

1. Date Detection: The app fetches the system time and converts it to the corresponding Hebrew date.
2. Rule Matching: It iterates through a list of month-based and date-specific rules.
3. Result Display: * Green/Blue UI: Indicates Tachanun is omitted.
   • Standard UI: Indicates Tachanun is recited.
4. Mincha Logic: If tomorrow is a day where Tachanun is omitted, the app displays a notice during the current day's Mincha window.

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🔌 JSON feed and rules module (for other displays)

The decision logic lives in one dependency-free file, lib/tachanun.js, which the page, the tests and the feed generator all load. A rule change there reaches all three at once, and LOGIC_VERSION inside it is bumped whenever an answer changes.

Every deploy also publishes a machine-readable feed under /feed/:

File	Contents
/feed/latest.json	this civil year and the next, every date
/feed/tachanun-YYYY.json	one civil year
/feed/index.json	what is published, with versions

Each file carries schema_version, logic_version and generated_at. Each date has today (daytime Shacharis and Mincha, with the Hebrew date), after_sunset (the Hebrew day that begins at nightfall, for displays that switch at their own local sunset) and krias_shema (the night that follows). The three "custom varies" days (3 Tammuz, 18 Elul, 5 Teves) are published with varies: true and recite: true; a display with its own setting for them should apply it. Consumers should cache by civil date and keep serving the cached copy if a fetch fails; a different schema_version major means the shape changed.

Locally: npm test runs the rules tests, npm run build:feed writes feed/ (ignored by git; the Pages workflow builds it on every deploy).

Attribution is required when the feed is shown elsewhere (CC BY-NC 4.0).

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🤝 Contributing

If you find a missing date or a bug in the calendar logic, feel free to open an issue or submit a pull request.

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⚖️ License

Distributed under the Creative Commons Attribution-NonCommercial 4.0 International License.

Note: Credit must be provided to the original author. For commercial use inquiries, please contact the repository owner via an Issue or the contact information provided in this profile.