it is FUNNY how even today there is no good mainstream way to work on web based GUi code. You can stare at static JSX or whatever and try to guess and simulate in your head. You can run the code. You can "inspect" in the browser. And it all still just sucks because of there being too much indirection, too many layers, too many transformations and expansions, and too many things that get in the way of iterating.
vs. what an actually good, interactive, helpful, development system could be.
(Mind you, is like a billion light years ahead of any old crap like Qt/C++.)