How I shipped a Nadi (BNN) astrology calculator as one 200 KB HTML file

Description and use

An offline, single‑file Nadi astrology calculator that runs from disk on a phone, using an inlined Astronomy Engine and a fixed UTC offset.

Problem

Deliver a Vedic astrology tool that runs offline from a single HTML file on a phone, without any build step, npm, server, or network calls.

Outcome

A fully offline, single‑file Nadi astrology calculator that runs on a phone without internet, with a final size of 206 KB.

Workflow

• 1. Inline the Astronomy Engine UMD bundle into the HTML, ensuring the Closure runtime shim ($jscomp) is included by starting the slice at byte 0.
• 2. Replace the external ephemeris and timezone APIs with local data and a fixed UTC offset selectable by the user.
• 3. Implement Nadi bond calculation by grouping planets by sign and determining leading planets based on degree order.
• 4. Compute slow‑planet progression by assigning years per sign for each planet and handling retrograde motion with fractional transitions.
• 5. Concatenate the engine and UI code into one file, test the inlined bundle in isolation, and host the final file on GitHub Pages.
• 6. Publish the source on GitHub under an MIT license for reuse.

Evidence

The tool had to run from a single file, opened straight from disk, on a phone, with no internet.

Source

Astronomy Engine ships as a UMD bundle. Dropping it into a <script> tag works — it detects the absence of module and define and assigns itself to window.Astronomy.

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ReferenceError: $jscomp is not defined

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The timezone database. A real tz database is large, and historical offsets for India alone are messy. I replaced it with a fixed UTC offset the user selects.

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The whole thing is 206 KB and works on a plane.

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