https://www.youtube.com/watch?v=Qlr-FGbhKaI&feature=youtu.be You cannot turn off ASI within Javascript, so there are also some cases creating errors even by using semicolons permanently. In essence: Using semicolons or not is not a matter of protecting your code in a better way. It is a convenience decision of you and/or your team. Some people want to use them, others don't use them. It is totally ok. There are better tools, especially linting based, e.g.. standard.js - they are able to detect most edge cases.

The "webserver" functionality of create-react-app is based upon webpack (wepback-dev-server) and not on basic node/express. To change that and to combine it with node/express api inherently, this would probably require a major rewrite in "manual mode" of the create-react-scripts. An easier solution is to run both in parallel and for the purpose that the client can work on the same port 3000 (to avoid cross-origin), webpack-dev-server can be configured as a proxy for node/express (running on 3001). A very good tutorial for that could be found at: https://www.fullstackreact.com/articles/using-create-react-app-with-a-server/

I think this chapter within the react docs is quite self-explanatory: https://facebook.github.io/react/docs/conditional-rendering.html