
Use the Scripter Script Editor in Logic Pro for Mac
The Script Editor is used to edit JavaScript code, enabling you to write your own MIDI plug-ins. Plug-in creation is in real time, which means that you can change and test your plug-in functions immediately. You can define interface elements, such as sliders and menus, that are shown in the Scripter plug-in window and can create the underlying logic and functions addressed by these onscreen controls. Some examples of utilities you can create with the Scripter plug-in are a chord strummer, a legato processor for stringed instruments, a harp glissando generator, and an algorithmic composer.
Important: The version of JavaScript used by the Scripter plug-in is determined by the JavaScriptCore framework version installed on your system. To ensure the greatest level of compatibility, install the latest Software Updates.
See the Scripter API overview for Scripter API documentation and code examples.

Script Editor parameters
Run Script button: Evaluate the script and configure the plug-in and parameters. Output, including errors, is shown in the Interactive Console when you click this button.
Code Editor: Type JavaScript code in this area. The editor provides the following features:
Syntax highlighting for JavaScript keywords and the available MIDI API (Application Programming Interface).
Live syntax checking, which highlights error lines immediately, making it easier to write your scripts.
Line numbers, which are useful for error checking because they are reported by line number in the Interactive Console.
Interactive Console: Displays debugging information and allows you to execute code on the command prompt by typing after the prompt and pressing Return. Type clear and press Return to clear the console.
Create and store a Scripter plug-in
In Logic Pro, open the Scripter plug-in.
Click the Open Script In Editor button.
Type (or copy and paste existing) JavaScript code in the Code Editor.
Click the Run Script button.
Test your plug-in to verify it behaves as intended.
Assuming no errors are shown in the Interactive Console, save the host document, setting, or patch containing the script.