Setting variables per environment electron-react app

its the first time i do electron app, this app need to do API calls to lets say:

http:/<baseUrl>/someAPI

I need to change this "baseURL" on build somehow. (can be anything...) and cant use System.env when app is build. i am using electron builder

I am thinking about creating a script and adding it to "package.json", any thing more simple?

Thanks!

#reactjs