Generate JSON type definition file with Tern.js's condense utility

I'm trying to use Tern's condense script to generate a type definition file for the p5.js Javascript library.

The Tern documentation says: "Pass --plugin name or --plugin name={jsonconfig} to load plugins. Use --def file to load JSON definitions."

I put the p5.js source code in the project's root and ran node condense --plugin ../p5/p5.js

I'm getting reference errors for all window, screen, and document-related functions, which makes me think the command is trying to run p5.js files, not analyze them.

Am I structuring the command incorrectly? Do I need a .tern-project file for this?

via Jen Kagan