learn-react-next-js https://nextjs.org/learn/foundations/from-javascript-to-react/essential-javascript-react https://developer.chrome.com/docs/devtools/dom/ https://beta.reactjs.org/learn/preserving-and-resetting-state#the-ui-tree https://beta.reactjs.org/learn/reacting-to-input-with-state#how-declarative-ui-compares-to-imperative