我该如何编写Google chrome扩展名，以便我可以通过javascript使用它？

I have two implementation of Python and Go as stand-alone application which runs in user desktop, now the user goes to www.VPN-myprivate-VPN.com website and logs in.

After login via Chrome the user need to communicate with the python/go application using javascript from the browser code.

Is there any sample available to work with, so that javascript > to google chrome my extension > to local system access

Any suggestion please?