This project demonstrates lifting state up and "thinking in react" by maintaining state where needed and using props to push state down to children.
The App class maintains state, higher up the DOM hierarchy. Radio buttons do not maintain their own state; they are "instructed" how to be set by props, which are sent from the parent.
When the user clicks a radio button, the changed value is lifted up through several layers of classes into the App. If the app were fleshed out, this state might be saved to a datastore on a server. In this case, it's just stored as state and redisplayed in the browser.
Here is a view:
This project was bootstrapped with Create React App.
In the project directory, you can run:
Runs the app in the development mode.
Open http://localhost:3000 to view it in the browser.