$scope.selectedIndex = 0;
    $scope.$watch('selectedIndex', function(current, old) {
            switch(current) {
                case 0:
                    $location.url("/homepage");
                    break;
                case 1:
                    $location.url("/i-piu-cliccati");
                    break;
                case 2:
                    $location.url("/i-piu-nuovi");
                    break;
                case 3:
                    $location.url("/per-categoria");
                    break;
            }