The following code is part of index.html (now renamed into index.php) and used for Firebase authentication. Because it's a flutter project, I was already looking for it on their websites. Unfortunately everybody can see the credentials easily by view HTML source code in browsers. I renamed the index.html into index.php and like to assign the Firebase auth constants in a separate php file (lets call it credentials.php). How to do it properly in order that it works? Here is the essential part of index.php:
<!-- Firebase Configuration -->
<script>
var firebaseConfig = {
apiKey: "AIzaSyxxx",
authDomain: "xxx.firebaseapp.com",
projectId: "xxx",
storageBucket: "xxx.appspot.com",
messagingSenderId: "xxxx",
appId: "xxx",
measurementId: "xxx"
};
const app = initializeApp(firebaseConfig);
// Initialize Firebase
</script>
All my attempts failed. How to do it properly in order that it works?