@fusionstrings/swiss-eph

Swiss Ephemeris astronomical calculation library compiled to WebAssembly for cross-platform JavaScript/TypeScript usage, with idiomatic Rust bindings.

Features

• Cross-platform: Works in Deno, Node.js, browsers, and edge runtimes (Cloudflare Workers)
• Rust Bindings: Complete FFI and safe Rust API for native performance
• High precision: Bit-level accuracy matching native Swiss Ephemeris calculations
• Complete API: 95+ functions for planetary positions, houses, eclipses, and more
• Zero dependencies: Self-contained WASM module with built-in Moshier ephemeris
• TypeScript: Full type definitions with TSDoc documentation

Installation (JS/TS)

Deno / JSR

import { load } from "jsr:@fusionstrings/swiss-eph";

Node.js / npm

npm install @fusionstrings/swiss-eph

import { load } from "@fusionstrings/swiss-eph";

Quick Start (JS/TS)

import { Constants, load } from "@fusionstrings/swiss-eph";

// Initialize the Swiss Ephemeris
const eph = await load();

// Calculate Julian Day for a date
const jd = eph.swe_julday(2024, 6, 15, 12.0, Constants.SE_GREG_CAL);

// Get Sun's position
const { xx, error } = eph.swe_calc_ut(
  jd,
  Constants.SE_SUN,
  Constants.SEFLG_SPEED,
);
console.log(`Sun longitude: ${xx[0]}°`);

Rust Usage

Add this to your Cargo.toml:

[dependencies]
swiss-eph = "0.1.0"

Quick Start (Rust)

use swisseph_x::safe::*;
use swisseph_x::*;

fn main() {
    let jd = julday(2024, 1, 1, 12.0);
    let flags = CalcFlags::new().with_speed();
    let sun = calc(jd, SE_SUN, flags).unwrap();
    println!("Sun longitude: {:.6}°", sun.longitude);
}

API Overview (JS/TS)

| Function | Description | | ------------------------------ | --------------------------- | | swe_calc / swe_calc_ut | Planetary positions (TT/UT) | | swe_houses / swe_houses_ex | House cusps and angles | | swe_julday / swe_revjul | Julian Day conversions | | swe_sidtime | Sidereal time | | swe_deltat | Delta T (TT - UT) |

License

AGPL-3.0 - Same license as the Swiss Ephemeris library.

This software is based on the Swiss Ephemeris by Astrodienst AG. See https://www.astro.com/swisseph/ for more information.

Credits

• Swiss Ephemeris by Astrodienst AG
• WASM compilation using WASI SDK and wasmbuild