A progressive web app can work offline, add to homescreen and even more performance wins!
VuePack is using offline-plugin so that your project will become offline ready by caching all (or some) of the webpack output assets.
The offline-plugin is only used in production environment, so no need to worry about the cache during development ;) Check out ./client/pwa.js / build/webpack.prod.js and offline-plugin to know more.