jsc-compile

Compile JavaScript to V8 bytecode — protect your source code and improve startup time.

Takes a bundled .js file and produces a zstd-compressed .jsc archive with pre-compiled V8 bytecode for 20+ Node.js LTS versions and 20+ Electron/VS Code versions, on linux-x64, win32-x64, and linux-arm64. No source code is shipped — only bytecode.

Install

npm install -g jsc-compile

Quick start

# 1. Bundle your project (e.g. with esbuild)
esbuild src/index.js --bundle --platform=node --format=cjs --outfile=dist/mylib.bundle.js

# 2. Compile to bytecode
jsc-compile dist/mylib.bundle.js -o dist/mylib.jsc

# Output:
#   mylib.jsc     — compressed bytecode archive (all targets)
#   index.js      — self-contained runtime loader

The generated loader has zero dependencies. Point your package.json at it and ship:

{
  "main": "index.js"
}

How it works

mylib.bundle.js
    │
    ▼  Generates a multi-stage Dockerfile
    │
    ▼  Docker BuildKit compiles in parallel:
    │    ├─ Node 24.x, 22.x, 20.x  ×  linux-x64
    │    ├─ Node 24.x, 22.x, 20.x  ×  win32-x64 (via Wine)
    │    ├─ Node 24.x, 22.x, 20.x  ×  linux-arm64 (via QEMU)
    │    ├─ Electron 33.x, 32.x …  ×  linux-x64
    │    ├─ Electron 33.x, 32.x …  ×  win32-x64 (via Wine)
    │    └─ Electron 33.x, 32.x …  ×  linux-arm64 (via QEMU)
    │
    ▼  Packs all .jsc into a single zstd-compressed archive
    │
    ├─ mylib.jsc      (~5% of raw size)
    └─ index.js       (~2 KB, self-contained)

At runtime the loader decompresses the archive, selects the bytecode matching the current Node/Electron version and platform, patches the V8 header, and loads it via vm.Script. No temp files, no native addons, no dependencies.

CLI options

jsc-compile <input>.js [options]

| Option | Default | Description | |---|---|---| | -o, --output <file> | <input>.jsc | Output archive path | | --no-electron | — | Skip Electron/VS Code targets | | --no-node | — | Skip Node.js LTS targets | | --no-local | — | Skip local Node.js version | | --no-wsl | — | Run Docker directly instead of via WSL (Windows) | | --docker-context <name> | — | Use a specific Docker context |

Prerequisites

• Node.js >= 22
• Docker with BuildKit support
• WSL on Windows (Docker commands are forwarded through WSL)
• Optionally, a named Docker context for remote builds (--docker-context my-builder)

Archive format

[4 bytes: index length (LE uint32)]
[N bytes: JSON index]
[remaining: concatenated .jsc blobs]
  └─ all zstd compressed

The JSON index maps keys like node_22.14.0_linux-x64 or electron_33.4.0_win32-x64 to { offset, size } entries.

License

ISC