class app.ServiceWorker  $.extend @prototype, Events   @isEnabled: ->    !!navigator.serviceWorker and app.config.service_worker_enabled   constructor: ->    @registration = null    @notifyUpdate = true     navigator.serviceWorker.register(app.config.service_worker_path, {scope: '/'})      .then(        (registration) => @updateRegistration(registration),        (error) -> console.error('Could not register service worker:', error)      )   update: ->    return unless @registration    @notifyUpdate = true    return @registration.update().catch(->)   updateInBackground: ->    return unless @registration    @notifyUpdate = false    return @registration.update().catch(->)   reload: ->    return @updateInBackground().then(() -> app.reboot())   updateRegistration: (registration) ->    @registration = registration    $.on @registration, 'updatefound', @onUpdateFound    return   onUpdateFound: =>    $.off @installingRegistration, 'statechange', @onStateChange() if @installingRegistration    @installingRegistration = @registration.installing    $.on @installingRegistration, 'statechange', @onStateChange    return   onStateChange: =>    if @installingRegistration and @installingRegistration.state == 'installed' and navigator.serviceWorker.controller      @installingRegistration = null      @onUpdateReady()    return   onUpdateReady: ->    @trigger 'updateready' if @notifyUpdate    return