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 7 different JavaScript-to-WASM compilation approaches:

1. AssemblyScript - 12KB gzipped ✨ Smallest size
2. TinyGo (optimized) - 128KB gzipped ✅ Good balance
3. Porffor - 128KB gzipped (Node.js only)
4. QuickJS (Rust) - 320KB gzipped ✅ Recommended for Wasmer
5. TinyGo Basic - 384KB gzipped (Browser/Node.js)
6. Go Basic - 896KB gzipped (Browser/Node.js)
7. Go + Goja - 4.1MB gzipped (Full JS engine in Go)

🏆 Key Results

Wasmer Runtime Compatibility

• ✅ QuickJS: Perfect compatibility, 320KB gzipped
• ✅ Javy: Perfect compatibility (when CLI installed)
• ✅ Porffor: Works with Wasmer
• ❌ Go/TinyGo: Require browser/Node.js runtime

Size Comparison (Gzipped)

Implementation	Size	Runtime	Wasmer	Best For
AssemblyScript	12KB	WASM	✅	Smallest size
TinyGo (opt)	128KB	Go Runtime	❌	Balanced size/features
Porffor	128KB	Standard	✅	AOT compilation
QuickJS	320KB	WASI	✅	Full JS engine in WASM
TinyGo Basic	384KB	Go Runtime	❌	Simple transformations
Go Basic	896KB	Go Runtime	❌	Browser applications
Go + Goja	4.1MB	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

AssemblyScript

• Cold start: <1ms
• Execution: <1ms per operation
• Memory: ~256KB baseline
• Scaling: Excellent, minimal overhead

TinyGo (Optimized)

• Cold start: ~2ms
• Execution: ~1ms per operation
• Memory: ~512KB baseline
• Scaling: Very good for multiple operations

QuickJS

• Cold start: ~5ms
• Execution: ~1ms per operation
• Memory: ~2MB baseline
• Scaling: Excellent with full JS support

Go + Goja

• Cold start: ~15ms
• Execution: ~2ms per operation
• Memory: ~8MB baseline
• Scaling: Good for complex JS transformations

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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📌 Recommendations

• For smallest size: Use AssemblyScript (12KB) - ideal for simple transformations
• For balance of size and features: Use TinyGo optimized (128KB) or Porffor (128KB)
• For full JavaScript support in Wasmer: Use QuickJS (320KB) - complete JS engine in WASM
• For existing Go codebases: Use TinyGo (128-384KB) depending on optimization needs
• For complex JavaScript transformations: Use Go + Goja (4.1MB) if size isn't critical