HTML - browser error --> Can't find variable: Firebase - html

Question

#jdv the error in the attached screenshot is being displayed in my browser's debugger
NOTE: Firebase DOES initializes in my command line - but my text editor will NOT accept the INITIALIZATION CODE (see code below). I love being challenged, but after 2 1/2 days of not finding a fix, I need help!
For some strange reason, config (in bold text below) is highlighted yellow in my text editor (I'm using brackets).
Here is some of my code:
<script src="/__/firebasejs/4.9.1/firebase-app.js"></script>
<script src="/__/firebasejs/4.9.1/firebase-auth.js"></script>
<script src="/__/firebasejs/4.9.1/firebase-database.js"></script>
<script src="/__/firebasejs/4.9.1/firebase-messaging.js"></script>
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>My App Title</title>
<script src="/__/firebasejs/4.9.1/firebase.js"></script>
<script>
// Initialize Firebase
var **config** = {
apiKey: "myapi",
authDomain: "myappname.firebaseapp.com",
databaseURL: "https://myappname.firebaseio.com",
projectId: "myprojectid",
storageBucket: "myappname.appspot.com",
messagingSenderId: "mysenderid",
};
firebase.initializeApp(config);
</script>
Perhaps someone can tell me what I am doing wrong. I am brand new to coding, so I beg your pardon if this is an easy fix :) -lion
Still searching for a solution....
Here is a screenshot of my code:
Thanks for all the helpful suggestions :) -lion

Answer 1

You should use
<script src="https://www.gstatic.com/firebasejs/4.9.0/firebase-app.js"></script>
<script src="https://www.gstatic.com/firebasejs/4.9.0/firebase-auth.js"></script>
<script src="https://www.gstatic.com/firebasejs/4.9.0/firebase-database.js"></script>
<script src="https://www.gstatic.com/firebasejs/4.9.0/firebase-messaging.js"></script>
<script src="https://www.gstatic.com/firebasejs/4.9.1/firebase.js"></script>
Instead of:
<script src="/__/firebasejs/4.9.1/firebase-app.js"></script>
<script src="/__/firebasejs/4.9.1/firebase-auth.js"></script>
<script src="/__/firebasejs/4.9.1/firebase-database.js"></script>
<script src="/__/firebasejs/4.9.1/firebase-messaging.js"></script>
<script src="/__/firebasejs/4.9.1/firebase.js"></script>