//Javascript
app.controller('ParentController', function($scope) { 
$scope.person = {greeted: false};
});
app.controller('ChildController', function($scope) {
$scope.sayHello = function() {
$scope.person.name = 'Ari Lerner';
};
});
//HTML
<div ng-controller="ParentController">
<div ng-controller="ChildController">
<a ng-click="sayHello()">Say hello</a>
</div>
{{ person }}
</div>
//result
{"greeted":true, "name": "Ari Lerner"}

app.controller('ParentController', function($scope) { 
$scope.$on('$fromSubControllerClick', function(e,data){
console.log(data); // hello
});
});
app.controller('ChildController', function($scope) {
$scope.sayHello = function() {
$scope.$emit('$fromSubControllerClick','hello');
};
});
//HTML
<div ng-controller="ParentController">
<div ng-controller="ChildController">
<a ng-click="sayHello()">Say hello</a>
</div>
</div>

angular
.module('MyApp')
.controller('MyController', ['$scope', '$rootScope', function MyController($scope, $rootScope) {
var unbind = $rootScope.$on('someComponent.someCrazyEvent', function(){
console.log('foo');
});
$scope.$on('$destroy', unbind);
}
]);

angular
.module('MyApp')
.config(['$provide', function($provide){
$provide.decorator('$rootScope', ['$delegate', function($delegate){
Object.defineProperty($delegate.constructor.prototype, '$onRootScope', {
value: function(name, listener){
var unsubscribe = $delegate.$on(name, listener);
this.$on('$destroy', unsubscribe);
return unsubscribe;
},
enumerable: false
});
return $delegate;
}]);
}]);

angular
.module('MyApp')
.controller('MyController', ['$scope', function MyController($scope) {
$scope.$onRootScope('someComponent.someCrazyEvent', function(){
console.log('foo');
});
}
]); 

var myApp = angular.module("myApp", []);
myApp.factory('Data', function() {
return {
name: "Ting"
}
});
myApp.controller('FirstCtrl', function($scope, Data) {
$scope.data = Data;
$scope.setName = function() {
Data.name = "Jack";
}
});
myApp.controller('SecondCtrl', function($scope, Data) {
$scope.data = Data;
$scope.setName = function() {
Data.name = "Moby";
}
});