Todd Motto's angular.extend instead of vm = this with private object

HTML

<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.4.3/angular.min.js"></script>
<div ng-app="app" ng-controller="loginController as vm">
    <input ng-model="vm.model.username" />
    <input ng-model="vm.model.password" />
    <button ng-click="vm.login()">Login</button>
</div>

JavaScript

angular.module('app', [])
    .controller('loginController', function loginController() {
        var model = {};
        function login() {
            alert('"this" vars: ' + model.username + ' | ' + model.password);
        }

       alert (this);

        angular.extend(this, {
            model: model,
            login: login
        });
});