force:showToast event handler in a VF page

force-showToast.js

var postEventToOneApp = function(name, params, fallbackAction) {
  if (SfdcApp && SfdcApp.projectOneNavigator && SfdcApp.projectOneNavigator.fireContainerEvent) {
    // Not officially supported by Salesforce
    SfdcApp.projectOneNavigator.fireContainerEvent(name, params);
  } else if (fallbackAction) {
    // Fallback if no Salesforce support of fireContainerEvent
    fallbackAction();
  }
};

$A.eventService.addHandler({
  event: 'force:showToast',
  handler: function(event) {
    postEventToOneApp('force:showToast', event.$params$, function() {
      alert(event.$params$.message);
    });
  }
});