I am using Angular and firebase for the backend to build an app. Many of my controllers will be working with firebase in someway. Should I just keep a ref to my firebase instance in the $rootScope or create a new one in each controller.
//at the top of each controller?
var ref = new Firebase(firebaseUrl);
Or
//set this once in app launch and use everywhere else
$rootScope.fbRef = new Firebase(firebaseUrl);