Run npm install to install necessary node modules. Then run npm run serve to launch the webpack dev server.
npm install
npm run serve
Install ngrok here https://ngrok.com/download
Use ngrok like ngrok http localhost:8080
If "Invalid Host Header" is given, use ngrok http 8080 -host-header="localhost:8080"
Then use the address provided by the ngrok interface to preview on your mobile device.