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

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.username" />
    <input ng-model="vm.password" />
    <button ng-click="vm.login()">Login</button>
</div>

JavaScript

angular.module('app', [])
    .controller('loginController', function loginController() {
    function login() {
        if(! this.username){
        alert("noooooooo");
        } else {
            alert('"this" vars: ' + this.username + ' | ' + this.password);
        }
        
    }

    angular.extend(this, {
        username: '',
        password: '',
        login: login
    });
});