The development server is even better.
npm install webpack-dev-server -g
webpack-dev-server --progress --colors
This binds a small express server on localhost:8080 which serves your static assets as well as the bundle (compiled automatically). It automatically updates the browser page when a bundle is recompiled (socket.io). Open http://localhost:8080/webpack-dev-server/ in your browser.
The dev server uses webpack's watch mode. It also prevents webpack from emitting the resulting files to disk. Instead it keeps and serves the resulting files from memory.