Flutter Web App，Firebase.auth 无法正常工作。试图调用一个非函数，比如null。 'dart.global.firebase.auth'答案

【问题标题】：Flutter Web App, Firebase.auth not working. Tried to call a non-function, such as null. 'dart.global.firebase.auth'Flutter Web App，Firebase.auth 无法正常工作。试图调用一个非函数，比如null。 'dart.global.firebase.auth'
【发布时间】：2020-10-19 01:38:27
【问题描述】：

我正在尝试使用 Firebase Auth 实现一个简单的 Flutter Web App。

我收到错误NoSuchMethodError: tried to call a non-function, such as null: 'dart.global.firebase.auth'。

我看过其他帖子，例如"NoSuchMethodError: tried to call a non-function, such as null: 'dart.global.firebase.auth'" when initializing auth() in flutter for web 和Flutter web: tried to call a non-function, such as null: 'dart.global.firebase.storage。

两者都提出了相同的解决方案：将 firebase-auth.js 添加到 index.html。我已经做到了。这就是我的index.html 文件的样子：

<!DOCTYPE html>
<html>
<head>
  <meta charset="UTF-8">
  <meta content="IE=Edge" http-equiv="X-UA-Compatible">
  <meta name="description" content="A new Flutter project.">

  <!-- iOS meta tags & icons -->
  <meta name="apple-mobile-web-app-capable" content="yes">
  <meta name="apple-mobile-web-app-status-bar-style" content="black">
  <meta name="apple-mobile-web-app-title" content="my_app">
  <link rel="apple-touch-icon" href="icons/Icon-192.png">

  <!-- Favicon -->
  <link rel="shortcut icon" type="image/png" href="favicon.png"/>

  <title>my_app</title>
  <link rel="manifest" href="manifest.json">
</head>

<body>
  <!-- This script installs service_worker.js to provide PWA functionality to
       application. For more information, see:
       https://developers.google.com/web/fundamentals/primers/service-workers -->
  
  <!-- Firebase Configuration-->
  <!-- The core Firebase JS SDK is always required and must be listed first -->
  <script src="https://www.gstatic.com/firebasejs/7.15.5/firebase-app.js"></script>

  <!-- TODO: Add SDKs for Firebase products that you want to use
      https://firebase.google.com/docs/web/setup#available-libraries -->
  <script src="https://www.gstatic.com/firebasejs/7.15.5/firebase-auth.js"></script>
  <!-- <script src="https://www.gstatic.com/firebasejs/7.15.5/firebase-analytics.js"></script>  -->
  <script src="https://www.gstatic.com/firebasejs/7.15.5/firebase-app.js"></script>
  <script src="https://www.gstatic.com/firebasejs/7.15.5/firebase-firestore.js"></script>
  <script src="https://www.gstatic.com/firebasejs/7.15.5/firebase-storage.js"></script>
  <script src="https://www.gstatic.com/firebasejs/7.15.5/firebase-database.js"></script>

  <script>
    // Your web app's Firebase configuration
    var firebaseConfig = {
      //my info
    };
    // Initialize Firebase
    firebase.initializeApp(firebaseConfig);
    // firebase.analytics();
  </script>
  <!-- End of Firebase Configuration-->
  
  <script>
    if ('serviceWorker' in navigator) {
      window.addEventListener('load', function () {
        navigator.serviceWorker.register('flutter_service_worker.js');
      });
    }
  </script>
  <script src="main.dart.js" type="application/javascript"></script>
</body>
</html>

感谢您的帮助！

【问题讨论】：

标签： firebase flutter firebase-authentication flutter-web

【解决方案1】：

原来我放了这个

<!-- Firebase Configuration-->
  <!-- The core Firebase JS SDK is always required and must be listed first -->
  <script src="https://www.gstatic.com/firebasejs/7.15.5/firebase-app.js"></script>

  <!-- TODO: Add SDKs for Firebase products that you want to use
      https://firebase.google.com/docs/web/setup#available-libraries -->
  <script src="https://www.gstatic.com/firebasejs/7.15.5/firebase-auth.js"></script>
  <!-- <script src="https://www.gstatic.com/firebasejs/7.15.5/firebase-analytics.js"></script>  -->
  <script src="https://www.gstatic.com/firebasejs/7.15.5/firebase-app.js"></script>
  <script src="https://www.gstatic.com/firebasejs/7.15.5/firebase-firestore.js"></script>
  <script src="https://www.gstatic.com/firebasejs/7.15.5/firebase-storage.js"></script>
  <script src="https://www.gstatic.com/firebasejs/7.15.5/firebase-database.js"></script>

  <script>
    // Your web app's Firebase configuration
    var firebaseConfig = {
      //my info
    };
    // Initialize Firebase
    firebase.initializeApp(firebaseConfig);
    // firebase.analytics();
  </script>
  <!-- End of Firebase Configuration-->

在错误的地方。

它应该在<head> 标签内。

附注，我有这个<script src="https://www.gstatic.com/firebasejs/7.15.5/firebase-app.js"></script> 两次，所以我删除了下面的那个。

最后，感谢 David Iglesias 在这里的回答：https://github.com/FirebaseExtended/flutterfire/issues/2860#issuecomment-651313186。

【讨论】：