React class Component with Sass + Webpack + Flow-type

The most difficult thing in my project is setting up the webpack🥲. There are lots of things that have to be set up, like loaders, modules, optimization .etc. As a newbie of bundle tools is a big challenge from start to finish.

In the past, I used to type npx run create-react-app , but rarely realized how it works. I choose to build my project step by step because I want to understand how modern web development does, not just build it in a quick way.

I'm not sure if my webpack.config.js file is accurate. Any feedback, I would appreciate.