swisseph-wasm 🌌

High-precision, WebAssembly bindings for the Swiss Ephemeris.

• 🚀 Best-in-Class: Faster, smaller, and more accurate than pure JS implementations.
• 🛡️ Safe: Rust-based memory safety for FFI interactions.
• 📦 Universal: Works in Node.js, Deno, Bun, and Browsers.

Features

• Full Swiss Ephemeris: Wraps the complete C library (v2.10.03).
• Zero Dependencies: Generated WASM has no external runtime deps.
• Type-Safe: Complete TypeScript definitions.
• Isomorphic: Runs everywhere WebAssembly runs.

⚡ Benchmarks

1. Complex Calculations (e.g. Moon Position)

When precision matters, swisseph-wasm is both faster and more accurate.

2. Simple Calculations (e.g. Sun Position)

For simple calculations, the overhead of calling WebAssembly dominates. Pure JS is faster here.

Summary: Use swisseph-wasm for professional-grade astrology (precision + complex speed). Use astronomy-engine for UI/visualizations (low precision + simple speed).

Run them yourself:

deno task bench
deno run -A benches/deno_throughput.ts
# For browser: Serve root and open benches/browser_bench.html

Installation

Deno / JSR

deno add jsr:@fusionstrings/swisseph-wasm

Rust (Cargo)

Use as a native Rust crate:

cargo add swisseph-wasm

Advanced: Import raw WASM (Deno):

import wasmBytes from "@fusionstrings/swisseph-wasm/wasm";
const module = new WebAssembly.Module(wasmBytes);

NPM / Node.js

npm install @fusionstrings/swisseph-wasm

Browser (Zero-Config)

Use the bundled browser version (inlined WASM) directly:

import { swe_julday } from "@fusionstrings/swisseph-wasm/browser";
// WASM initializes automatically

Quick Start

import {
  SE_GREG_CAL,
  SE_MOON,
  SE_SUN,
  swe_calc_ut,
  swe_julday,
} from "@fusionstrings/swisseph-wasm";

// 1. Calculate Julian Day for Jan 1, 2000, 12:00 UTC
const jd = swe_julday(2000, 1, 1, 12.0, SE_GREG_CAL);
console.log(`Julian Day: ${jd}`); // 2451545.0

// 2. Calculate Sun Position
const sun = swe_calc_ut(jd, SE_SUN, 0);
console.log("Sun Longitude:", sun.longitude);

// 3. Calculate Moon Position
const moon = swe_calc_ut(jd, SE_MOON, 0);
console.log("Moon Longitude:", moon.longitude);

Building from Source

Prerequisites

• Rust: rustup target add wasm32-unknown-unknown
• Deno: For task management.
• LLVM: Required for compiling the C library to WASM.

macOS Users:

brew install llvm

Build Command

The build script automatically detects Homebrew LLVM.

deno task build

Maintenance

Version Management

To update the version across Deno, Cargo, and NPM configs:

deno task bump-version <new-version>
# Example: deno task bump-version 1.2.3

This command validates the version format, updates all config files, and syncs Cargo.lock.

License

MIT License. Based on the Swiss Ephemeris (GPL/Commercial dual license). Note: Using this library implies compliance with the Swiss Ephemeris license terms.