App Visibility     

Quasar makes use of the Web Page Visibility API which lets you know when a website/app is visible or in focus.

import { AppVisibility } from 'quasar'

(Boolean) AppVisibility.isVisible()

There is also an event triggered when focus changes (read about Quasar Global Event Bus here):

Event NameParametersDescription
app:visibility(String) stateApp got focus if state is visible or lost focus if state is hidden