AngularJS 1.0轮播图

angular.module('M12', ['ng']).
  controller('C12', function($scope, $interval){
    $scope.num = 1;
    $scope.pro = function(){
      $interval.cancel(t);
      $scope.num > 1 ? $scope.num-- : $scope.num = 5;                
    }
    $scope.next = function(){
      $interval.cancel(t);
      $scope.num < 5 ? $scope.num++ : $scope.num = 1;
    }
    let t = $interval(function(){
      $scope.num < 5 ? $scope.num++ : $scope.num = 1;
    }, 1000)
  })