I think it would be interesting if this works with source-maps, that are created from things like webpack or compilers/transpilers. The unused code which ends-up in the browser might result from unused code in original files which looks slightly differently, and it's interesting where it comes from.

Webpack bundles everything up into one huge .js file, I gotta try how it works with that.

Plus in my current environment (ReactJS + TypeScript + MobX + Webpack) tslint generates errors when I have unused variables and that breaks TeamCity build.

No matter what, this tool is super useful!

You can do code splitting with Webpack it's a matter of config and how your code is organized. https://webpack.github.io/docs/code-splitting.html