Angular: Empty Fiddle

http://angularjs.org/

HTML

<div ng-controller="MyCtrl"> 
    <a href ng-click="add()">add</a>
    <div my-dir attr4="obj.prop4"></div>
    {{obj.prop4}}
</div>

JavaScript

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

myApp.directive('myDir', function () {
    return {
        scope: {
            at: '=attr4'
        },
        link: function (scope, element, attrs) {
            scope.$watch('at', function (value) {
                console.log('attr', value, scope.at);
            });
        }
    };
});


function MyCtrl($scope) {
    $scope.obj = { prop4: 1 };
    $scope.add = function () {
        $scope.obj.prop4++;
    };
}