Hi John Clark,
So no expert here but have done a bit research on the topic and can offer the following insights...
It seems that vanilla JS requires the use of a browser and as a result I'm pretty sure you are stuck with HTTP through requests / fetch / websockets....
I would recommend looking at Node.js which has the ability to do this. This can be vanilla js if you are just using node instead of the browser to house the code.
I hope this information helps guide you to the desired solution for your project.
Is this possible or am I going to have to use some other framework to make this happen in a local web app? I've just started learning JS, so I don’t really have a good idea how to implement this and haven't been able to find good examples.
If JS won’t work, I'd welcome any suggestions of how I could create a local web app that can send VISCA commands.