add firebase javascript
// Create Firebase project
// Create Web app in Firebase console
// Link project
var firebaseConfig = {
apiKey: // apiKey,
authDomain: // authDomain,
databaseURL: // databaseURL,
projectId: // projectId,
storageBucket: // storageBucket,
messagingSenderId: // messagingSenderId,
appId: // appId,
measurementId: // measurementId
};
firebase.initializeApp(firebaseConfig);
// Add your dependencies
//E.G.
<script src="https://www.gstatic.com/firebasejs/7.21.1/firebase-app.js"></script>