I've always found it weird that many people put the HTML, JS, and CSS for one component in three different files, but never thought enough about it to put it in

I've always found it weird that many people put the HTML, JS, and CSS for one component in three different files, but never thought enough about it to put it into words. Pete Hunt (one of React's maintainers) does that here: https://www.youtube.com/watch?v=DgVS-zXgMTk https://www.youtube.com/watch?v=DgVS-zXgMTk React is about separating concerns, not technologies. Everything you need to know to draw an App Bar is in AppBar.jsx. You can dynamically generate the markup with JavaScript, but that doesn't change your separation of concerns, because everything concerning that component lives in that file.