官方文件看得很頭痛,還好有影片輔助,但這是兩者皆要,才能達成。
而影片看完後 覺得滿easy的,其實是他教得很有條理、淺顯易懂,
跟著做 結果 卡在 Cannot read property 'FacebookAuthProvider' of undefined
想說都造做了 怎麼會 ! ! ! 晴天霹靂 ! ! !
開始找可能原因
設定沒問題(fb developer&firebase), config 有回傳,
剩Script 沒 include 到~~~ 但其實 不知道哪個沒include到。
後來老大救援 ,找到一個 Stackoverflow 的資源 ,補了一個 js script。 就 O K 啦 XDDD
如果沒有老大的救援,我可能宣告陣亡 置之不理 QQ
Step 0 : 申請 facebook developer + firebase
Step 1 : 連接 fb & firebase
 
 


- Create an instance of the Facebook provider object

- Authenticate with Firebase using the Facebook provider object. You can prompt your users to sign in with their Facebook accounts either by opening a pop-up window or by redirecting to the sign-in page. The redirect method is preferred on mobile devices.

貼到 html (body) 的 Firebase SDK snippet 的下方
Step 4 : 官方文件 沒有特別提到(或是我沒注意到) 要 include 進來的 script ,放 firebaseConfig 前面
<script src="https://www.gstatic.com/firebasejs/5.9.1/firebase-auth.js"></script>
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width,initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Tyy it</title>
</head>
<body>
    <!-- The core Firebase JS SDK is always required and must be listed first -->
<script src="https://www.gstatic.com/firebasejs/6.5.0/firebase-app.js"></script>
<script src="https://www.gstatic.com/firebasejs/5.9.1/firebase-auth.js"></script>
<script>
  // Your web app's Firebase configuration
  var firebaseConfig = {
    apiKey: "",
    authDomain: "fb-login-df75e.firebaseapp.com",
    databaseURL: "https://fb-login-df75e.firebaseio.com",
    projectId: "fb-login-df75e",
    storageBucket: "",
    messagingSenderId: "981102618300",
    appId: "1:981102618300:web:685947c929db7343"
  };
  // Initialize Firebase
  var a = firebase.initializeApp(firebaseConfig);
  console.log(a)
</script>
    <script>
       var provider = new firebase.auth.FacebookAuthProvider()
 firebase.auth().signInWithPopup(provider).then(function(result) {
  // This gives you a Facebook Access Token. You can use it to access the Facebook API.
  var token = result.credential.accessToken;
  // The signed-in user info.
  var user = result.user;
  // ...
}).catch(function(error) {
  // Handle Errors here.
  var errorCode = error.code;
  var errorMessage = error.message;
  // The email of the user's account used.
  var email = error.email;
  // The firebase.auth.AuthCredential type that was used.
  var credential = error.credential;
  // ...
});
    </script>
</body>
</html>
不封鎖 彈出視窗 ,程式碼的部分是用 Popup 的方式彈出 fb 的登入視窗 ,一旦封鎖了,等於看不到效果。 


如果 以Google 帳號的方式登入 ,只需要在firebase 啟用 Google,然後 Code 的 instance 改成下面這行,即可使用Google 第三方登入。
 var provider = new firebase.auth.GoogleAuthProvider()
