Using variables in clips.json

I’m attempting to port over the popular VS-Code snippet library, ES7 - Javascript - React - Snippets.
I thought it would be possible to insert some of the primary Nova variables into the clips.json file in order to expand into their values, for example, to name a function after its filename, I thought I would do something like:
“content”: “function $FileBasename() {}” , but that doesn’t seem to work as expected. I have gotten the $FILENAME variable to work, but that pulls in the entire filename, including the extension, which we don’t want.
I’m sure I’m doing something silly, first time working on any sort of extension so bear with me…