JavaScript to WebAssembly Compilation Comparison

A comprehensive analysis and comparison of different approaches to compile JavaScript to WebAssembly, with a focus on size optimization and runtime compatibility.

🎯 Overview

This repository explores 5 different JavaScript-to-WASM compilation approaches:

1. QuickJS (Rust) - 262KB gzipped ✅ Recommended for Wasmer
2. Javy Static - 519KB gzipped ✅ Wasmer Compatible
3. Javy Dynamic - 488KB + 2KB per module (Node.js only)
4. Porffor - 75KB gzipped (Node.js only)
5. Go/TinyGo + Goja - 92KB-3.7MB gzipped (Browser/Node.js only)

🏆 Key Results

Wasmer Runtime Compatibility

• ✅ QuickJS: Perfect compatibility, 262KB gzipped
• ✅ Javy Static: Perfect compatibility, 519KB gzipped
• ❌ All others: Require Node.js runtime or have compatibility issues

Size Comparison (Gzipped)

Implementation	Size	Runtime	Wasmer	Best For
QuickJS	262KB	WASI	✅	Production Wasmer
Javy Static	519KB	WASI	✅	Full JS Compatibility
Porffor	75KB	Standard	❌	Size-critical Node.js
TinyGo Basic	92KB	Go Runtime	❌	Browser applications
Javy Dynamic	490KB	WASI	❌	Node.js multi-module
Goja	3.7MB	Go Runtime	❌	Full JS engine in Go

🚀 Quick Start

Prerequisites

• Go 1.21+
• Rust with wasm32-wasip1 target
• Node.js 18+
• Javy
• Porffor
• Wasmer (optional, for testing)

Build All Implementations

# Install dependencies
make install-deps

# Build all implementations
make build-all

# Test all implementations
make test-all

# Test Wasmer compatibility
make test-wasmer

Build Individual Implementations

QuickJS (Recommended)

cd implementations/quickjs
cargo build --release --target wasm32-wasip1

Javy Static

cd implementations/javy
javy build -o transform.wasm transform.js

Porffor

cd implementations/porffor
porffor transform.js -o transform.wasm

📊 Detailed Analysis

Performance Characteristics

QuickJS

• Cold start: ~5ms
• Execution: ~1ms per operation
• Memory: ~2MB baseline
• Scaling: Excellent for multiple operations

Javy Static

• Cold start: ~8ms
• Execution: ~1ms per operation
• Memory: ~3MB baseline
• Scaling: Good for multiple operations

Runtime Compatibility

WASI Compatible (Wasmer Ready)

• QuickJS: Perfect compatibility, uses standard WASI interfaces
• Javy Static: Perfect compatibility, self-contained

Node.js/Browser Only

• Porffor: Uses legacy WASM exceptions
• Go/TinyGo: Requires wasm_exec.js runtime
• Javy Dynamic: Needs dynamic linking support

🔧 Implementation Details

QuickJS Implementation

• Language: Rust
• Engine: QuickJS JavaScript engine
• Target: wasm32-wasip1
• Features: Full ECMAScript support, WASI I/O

Javy Implementation

• Language: JavaScript
• Engine: QuickJS (via Javy)
• Target: WASI
• Features: Bytecode Alliance quality, multiple build modes

Porffor Implementation

• Language: JavaScript
• Engine: AOT compiled
• Target: Standard WASM
• Features: Smallest size, compile-time optimization

📁 Repository Structure

├── implementations/
│   ├── quickjs/          # Rust + QuickJS (RECOMMENDED)
│   ├── javy/             # Javy static/dynamic builds
│   ├── porffor/          # Porffor AOT compilation
│   ├── goja/             # Go + Goja JavaScript engine
│   └── tinygo/           # TinyGo basic implementation
├── docs/
│   ├── BINARY_SIZES.md           # Detailed size analysis
│   ├── WASMER_COMPATIBILITY.md   # Runtime compatibility guide
│   ├── JAVY_WASMER_ANALYSIS.md   # Javy-specific analysis
│   └── FINAL_WASMER_SUMMARY.md   # Executive summary
├── tests/                # Test suites and benchmarks
├── Makefile             # Build automation
└── README.md           # This file

🧪 Testing

Unit Tests

npm test

Wasmer Compatibility Tests

make test-wasmer

Size Analysis

make measure-sizes

Performance Benchmarks

make benchmark

📖 Documentation

• Binary Size Analysis - Comprehensive size comparison
• Wasmer Compatibility Guide - Runtime compatibility details
• Javy Analysis - Javy-specific findings
• Final Summary - Executive summary and recommendations

🔬 Research Findings

Wasmer v6.1.0-rc.2 Dynamic Linking

• Introduces dynamic linking for WASIX/C++ libraries
• Does NOT support WASM module import resolution
• Javy dynamic builds still require Node.js runtime

Size Optimization Techniques

• wasm-opt: 15-20% size reduction
• Compression: 60-70% reduction with gzip
• Dead code elimination: Significant impact on Go builds

Runtime Performance

• WASI overhead: Minimal (~1ms)
• JavaScript engine startup: 5-10ms
• Execution performance: Comparable to native JavaScript

🤝 Contributing

1. Fork the repository
2. Create a feature branch
3. Add your implementation in implementations/
4. Update documentation and tests
5. Submit a pull request

📄 License

MIT License - see LICENSE for details.

🙏 Acknowledgments

• Bytecode Alliance for Javy
• Wasmer for the excellent WASM runtime
• QuickJS for the JavaScript engine
• Porffor for AOT JavaScript compilation
• TinyGo for efficient Go compilation

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For production Wasmer deployment, use QuickJS (262KB) for optimal size or Javy Static (519KB) for maximum JavaScript compatibility.