@cooljapan/oxiephemeris

A full Western-astrology chart engine as WebAssembly — compute natal charts, synastry, transits, secondary progressions, and midpoint composites, plus their Linked Open Data (RDF Turtle / N-Triples with SKOS and PROV-O), entirely in the browser. No server, no upload: the JPL DE ephemeris file you supply never leaves the page.

Published to npm as @cooljapan/oxiephemeris.

Install

npm install @cooljapan/oxiephemeris

import init, { natal_json, natal_turtle } from '@cooljapan/oxiephemeris';
await init();

Build from source

Local/demo build (unscoped, target web — what www/index.html actually uses via a relative import):

wasm-pack build crates/oxiephemeris-wasm --target web --out-dir pkg

Published-package-shaped build (matches CI):

wasm-pack build crates/oxiephemeris-wasm --scope cooljapan --target bundler --out-dir pkg-bundler

Use (browser / ES modules)

import init, { natal_json, natal_turtle } from './pkg/oxiephemeris_wasm.js';
await init();

// DE440/DE441 bytes, e.g. from <input type="file"> → arrayBuffer():
const de = new Uint8Array(buffer);
// The Unix epoch at the Royal Observatory, Greenwich.
const req = JSON.stringify({ date: "1970-01-01T00:00:00Z", lat: 51.4779, lon: 0.0 });

const chart = JSON.parse(natal_json(de, req));
const sun = chart.bodies.find(b => b.body === "Sun");
// -> Capricorn, 10.16°, house 4

const turtle = natal_turtle(de, req);   // RDF Turtle with SKOS + PROV-O

crates/oxiephemeris-wasm/www/index.html is a self-contained demo page.

Functions

Each takes the DE bytes and a JSON request string, and returns a JSON (or Turtle) string:

• natal_json(de, req) / natal_turtle(de, req, base_iri?)
• synastry_json(de, req) / synastry_turtle(de, req, base_iri?)
• transit_json(de, req)
• progress_json(de, req)
• composite_json(de, req) / composite_turtle(de, req, base_iri?)

The request/response schemas are identical to the Python binding and the CLI, so results are bit-for-bit the same across all three.

Apache-2.0.