angularjs - how to broadcast and emit events to other controllers in angular that have no parent-child relationship -

i trying hints post - working $scope.$emit , $scope.$on nothing seems work when controllers in no way related each other.

that -

and in ctrlb this:

$rootscope.$broadcast('userhasloggedin', {})

and in ctrla listen so:

$rootscope.$on('userhasloggedin, function(event, data){});

and no - ctrla never receives broadcasted event unless nest ctrlb div inside ctrla div

any idea?

it tough answer without knowing tried. please see plnkr: http://plnkr.co/edit/hyzworgeypllcmzndco2?p=preview

i created 2 controllers, 1 sends text other:

app.controller('ctrla', function($scope, $rootscope) {   $scope.submit = function(){     $rootscope.$broadcast('userhasloggedin', $scope.input);   }  });  app.controller('ctrlb', function($scope) {   $scope.$on('userhasloggedin', function(event, data){     $scope.data = data;    });    $scope.data = 'nothing'; });