AngularJS service rootscope

$digest() only "flushes" the current scope and all of its child scopes.

$apply(exp) evaluates the exp and then calls $digest() on the root scope. So calling $apply() (on any scope) affects all scopes.

If you call $digest() and your action changes some parent scope, the change will not be observed. So normally you want to call $apply(). (If you're tempted to try and be more efficient by calling $digest(), it can bite you later!)

There's only one root scope per application. Calling $rootScope.$apply() will trigger a digest cycle that will dirty check the entire scope tree.

To avoid this, call $apply from the controller's scope or its parent scope if you want to dirty-check multiple sibling scopes.

The code below will log MyCtrl and MyCtrl2 to the console every two seconds, suggesting that any $apply to any $scope, will digest all scopes. The question is against which scope the applied function will run. If it dirty check only the applied scope, the MyCtrl shouldn't be logged. Fiddle here.

var mod = angular.module('MyApp', []);

mod.controller('MyCtrl', function($scope) {
    $scope.value = function() {
        console.log('MyCtrl');
        return 'value';
    };

    setInterval(function() {
        $scope.$apply()
    }, 2000);
});

mod.controller('MyCtrl2', function($scope) {
    $scope.value2 = function() {
        console.log('MyCtrl2');
        return 'value 2';
    };
});​

<div ng-app="MyApp">
  <div ng-controller="MyCtrl">{{value()}}</div>
  <div ng-controller="MyCtrl2">{{value2()}}</div>
</div>​