title: Firebase - Web Chat App sign in button doesn't work
body: <p>I use windows 8. I would like to build an app using <a href="https://codelabs.developers.google.com/codelabs/firebase-web/#0" rel="nofollow noreferrer">this guide.</a>. On 7 step, I change main.js file. My file content is below :</p>
  <pre><code>FriendlyChat.prototype.initFirebase = function() {
    this.auth = firebase.auth();
    this.database = firebase.database();
    this.storage = firebase.storage();
    this.auth.onAuthStateChanged(this.onAuthStateChanged.bind(this));
  };
  
  
  FriendlyChat.prototype.signIn = function(googleUser) {
  
     var provider = new firebase.auth.GoogleAuthProvider();
    this.auth.signInWithPopup(provider);
  };
  
  FriendlyChat.prototype.signOut = function() {
    this.auth.signOut();
  };
  
  FriendlyChat.prototype.onAuthStateChanged = function(user) {
  if (user) { // User is signed in!
    var profilePicUrl = user.photoURL; // Only change these two lines!
    var userName = user.displayName;   // Only change these two lines!
    ....
  }
  
  FriendlyChat.prototype.checkSignedInWithMessage = function() {
    if (this.auth.currentUser) {
      return true;
    }
    ....
  </code></pre>
  <p>I create a project using firebase console. I click &quot;Add Firebase to your web app&quot; and click the snippet. I paste it to index.html file. The file content is below :</p>
  <pre><code>&lt;script src=&quot;https://www.gstatic.com/firebasejs/live/3.0/firebase.js&quot;&gt;&lt;/script&gt;
  
  &lt;script&gt;
    // Initialize Firebase
    var config = {
      apiKey: &quot;AIzaSyAbtFJIZZxExBZec5XjsIE6p_TK4x-NDLE&quot;,
      authDomain: &quot;xxx-65704.firebaseapp.com&quot;,
      databaseURL: &quot;https://xxx-65704.firebaseio.com&quot;,
      storageBucket: &quot;xxx-65704.appspot.com&quot;,
    };
    firebase.initializeApp(config);
  &lt;/script&gt;    
  &lt;script src=&quot;scripts/main.js&quot;&gt;&lt;/script&gt;    
  &lt;/body&gt;
  </code></pre>
  <p>I run &quot;firebase serve&quot; command on cmd terminal. I open localhost:/5000and the page is below :</p>
  <p><a href="https://i.stack.imgur.com/a3YzC.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/a3YzC.png" alt="enter image description here" /></a></p>
  <p>It doesn't display web chat. So I open we-start/index.html, I click &quot;Sign in With Google&quot;. But I cannot sign in. I don't know how to fix this problem. What is my mistake?</p>