inject firebase in angularjs code example

Example: inject firebase in angularjs

<!-- AngularJS -->
<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.6.1/angular.min.js"></script>

<!-- Firebase -->
<script src="https://www.gstatic.com/firebasejs/3.6.6/firebase.js"></script>

<!-- AngularFire -->
<script src="https://cdn.firebase.com/libs/angularfire/2.3.0/angularfire.min.js"></script>