angularjs, coding style, use of global variable - angularjs

Question

I see a lot of Angular codes more like this.
The following one is from their tutorial.
angular.module('phonecat', ['phonecatFilters', 'phonecatServices']).
config(['$routeProvider', function($routeProvider) {
$routeProvider.
when('/phones', {templateUrl: 'partials/phone-list.html', controller: PhoneListCtrl}).
when('/phones/:phoneId', {templateUrl: 'partials/phone-detail.html', controller: PhoneDetailCtrl}).
otherwise({redirectTo: '/phones'});
}]);
However, I am more familiar with like this;
var app = angular.module('phonecat', ['phonecatFilters', 'phonecatServices']);
app.config(function($routeProvider) {
$routeProvider.
when('/phones', {templateUrl: 'partials/phone-list.html', controller: PhoneListCtrl}).
when('/phones/:phoneId', {templateUrl: 'partials/phone-detail.html', controller: PhoneDetailCtrl}).
otherwise({redirectTo: '/phones'});
}]);
I even want to define that function($routeProvider) { ...} as a variable, but I am not confident about that will work.
Is there a reason behind this to avoid global variable, in this case app.
Or it's just one of best practices in AngularJs community?

Answer 1

angular.module(..) returns a module, and you can;
assign to a variable app(which is a global variable).
or continue chaining it
You saw a lot of chained examples because it is in a single file.
You will also see a lot of examples using global variable 'app' or whatever, because codes needs to be organized to many files.
I recommend the first one if you make an single file example.
I recommend the second one if you make an actual app, which requires name spacing.

Answer 2

Namespacing is good. Best practive is using angular.value instead of global variables
app.value('myVariable', 'myValue')
.controller('myController', function($scope, myVariable) {
...
});