$rootScope.$broadcast vs. $scope.$emit
tl;dr (this tl;dr is from @sp00m's answer below)
$emit
dispatches an event upwards ...$broadcast
dispatches an event downwards
Detailed explanation
$rootScope.$emit
only lets other $rootScope
listeners catch it. This is good when you don't want every $scope
to get it. Mostly a high level communication. Think of it as adults talking to each other in a room so the kids can't hear them.
$rootScope.$broadcast
is a method that lets pretty much everything hear it. This would be the equivalent of parents yelling that dinner is ready so everyone in the house hears it.
$scope.$emit
is when you want that $scope
and all its parents and $rootScope
to hear the event. This is a child whining to their parents at home (but not at a grocery store where other kids can hear).
$scope.$broadcast
is for the $scope
itself and its children. This is a child whispering to its stuffed animals so their parents can't hear.
They are not doing the same job: $emit
dispatches an event upwards through the scope hierarchy, while $broadcast
dispatches an event downwards to all child scopes.