Very nice. I like that there is an option to set the inactivity threshold.

My method is considerably more primitive but works well enough. It's disturbing how long this process can take after a few npm installs.

  function nmpurge --description 'Recursively delete all node_modules folders' --argument target
      if test -z "$target"
          echo "Specify a directory to clean"
          return 1
      end

      find "$target" -name "node_modules" -type d -prune -exec rm -rf '{}' +
  end