Wrap Global Variables in Services

adoptingAngular_example1.js

// Instead of this:
angular.module('app', [])
  .controller('MyCtrl', function($scope) {
    // What is moment? How do I know this exists and is the right object?
    $scope.startTime = moment();
    $scope.endTime - moment().add(1, 'h');
  });
  
// Try this:
angular.module('app', [])
  .service('moment', function($window) {
    return $window.moment();
  })
  .controller('MyCtrl', function($scope, moment) {
    $scope.startTime = moment();
    $scope.endTime = moment().add(1, 'h');
  });