script.xml

<!-- The core Firebase JS SDK is always required and must be listed first -->
<script src="https://www.gstatic.com/firebasejs/9.XX.X/firebase-app-compat.js"></script>

<!-- Add Firebase products that you want to use -->
<script src="https://www.gstatic.com/firebasejs/9.XX.X/firebase-auth-compat.js"></script>
<script src="https://www.gstatic.com/firebasejs/9.XX.X/firebase-firestore-compat.js"></script>

<script>
  // Your web app's Firebase configuration
  // For Firebase JS SDK v7.20.0 and later, measurementId is optional
  const firebaseConfig = {
    apiKey: "YOUR_API_KEY",
    authDomain: "YOUR_PROJECT_ID.firebaseapp.com",
    projectId: "YOUR_PROJECT_ID",
    storageBucket: "YOUR_PROJECT_ID.appspot.com",
    messagingSenderId: "YOUR_MESSAGING_SENDER_ID",
    appId: "YOUR_APP_ID",
    measurementId: "YOUR_MEASUREMENT_ID"  // Optional
  };

  // Initialize Firebase
  firebase.initializeApp(firebaseConfig);

  const auth = firebase.auth();
  const db = firebase.firestore();
</script>