Why use $ rootScope to exchange data between controllers when factories can do the same?

Question

I understand that $ rootScope is some kind of global variable that allows it to be shared between controllers. Factories can also do the same. So why not use a factory instead? When should $ rootScope be used and when should factory be used, given that they accomplish almost the same purpose?

Answer 1

AngularJS FAQs are pretty good here :

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Answer 2

$rootScope . ( : , , - ), $rootScope.
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Answer 3

- (factory). $rootScope , , , . $rootScope , ($rootScope.$broadcast), / , .