Not him but I use typescript with webpack. Webpack has webpack serve, which runs a simple HTTP server that shows an index.html for testing your script. It adds some file watchers on your source so if you make any changes it automatically compiles. Webpack will build the .map files so you can run breakpoints in your browser on the original source, but if you develop with vscode, you can create a launch profile which allows you to attach your vscode debugger to the browser and put your breakpoints in VSCode instead of the browser (which I prefer the UI for). This works with react as well