@benjamindehli/logic-pro-script-compiler

Compiles JavaScript files to .pst files for the Logic Pro Scripter MIDI plugin.

Logic Pro's Scripter plugin uses a binary .pst format to store scripts. This tool takes standard .js source files, transpiles them for compatibility with Logic Pro's JavaScript engine, and packages them into the correct binary format, letting you write and maintain scripts in a modern editor with your usual tooling.

Requirements

• Node.js >= 16

Usage

One-off with npx

Run without installing, passing your own input and output directories:

npx @benjamindehli/logic-pro-script-compiler -i ./src -o ./build

Note: Do not run this from inside the logic-pro-script-compiler package directory itself. Run it from your own project.

Global install

npm install -g @benjamindehli/logic-pro-script-compiler
logic-pro-script-compiler -i ./src -o ./build

Options

| Flag | Alias | Description | Default | | ---- | ----- | ----------- | ------- | | --input | -i | Directory containing .js source files | ./src | | --output | -o | Directory to write .pst files to | ./build | | --help | -h | Show help | |

How it works

1. Transpile — Each .js file is passed through Babel with the following transforms:
   • const/let → var (block scoping)
   • Optional chaining (?.) → equivalent conditional expressions
   • Spread syntax (...) → explicit concatenation
2. Package — The transpiled source is wrapped in a binary bplist structure and written into the .pst chunk format that Logic Pro expects.

The output directory mirrors the structure of the input directory, so nested folders are preserved.

Example

Given this source tree:

src/
  DigiTech Whammy/
    MIDI Note to Whammy Pitch.js
  Elektron SidStation/
    Editor.js

Running:

npx @benjamindehli/logic-pro-script-compiler -i ./src -o ./build

Produces:

build/
  DigiTech Whammy/
    MIDI Note to Whammy Pitch.pst
  Elektron SidStation/
    Editor.pst

Each .pst file can be opened directly in the Logic Pro Scripter plugin.

Programmatic API

The package also exposes its internals for use in Node.js scripts:

const { buildBplist, transpile, compileToPst, processDirectory } = require("@benjamindehli/logic-pro-script-compiler");

transpile(jsSource) → string

Transpiles a JavaScript string using Babel. Returns the transpiled source code.

buildBplist(jsBytes) → Buffer

Wraps a UTF-8 Buffer of transpiled JavaScript in the bplist binary format. Throws if the script exceeds 65535 bytes.

compileToPst(jsSource) → Buffer

Transpiles and packages a JavaScript string into a complete .pst Buffer ready to be written to disk.

processDirectory(srcDir, buildDir)

Recursively walks srcDir, compiles every .js file found, and writes the resulting .pst files to the mirrored path under buildDir. Dotfiles and non-.js files are skipped.

License

GPL-3.0 © Benjamin Dehli