Devdependencies

Separating dependencies from devDependencies is really a matter of semantics when it comes to webpack-based projects, as webpack will inspect and tree-shake whatever dependencies you're using, irrespective of where they are allocated in package.json. The approach cited in this article of separating them still makes sense, as it helps folks understand your codebase, but it won't ultimately matter once the visual is packaged.

For a time, it was even a requirement for certification that a visual must only use devDependencies (here's an example of a visual I had to do this for), but I'm pretty sure this has recently been relaxed, although I'm still doing it out of habit for all the visuals I submit to AppSource.