Flutter：未捕获的 ReferenceError：未定义 firebase答案

【问题标题】：Flutter: Uncaught ReferenceError: firebase is not definedFlutter：未捕获的 ReferenceError：未定义 firebase
【发布时间】：2020-10-08 10:22:49
【问题描述】：

我在 Flutter Web 应用程序中使用 Firebase 服务，但在加载 firebase 脚本时遇到问题。

当我使用颤振时 run -d chrome 我看到空白页面有错误，并且在重新加载页面后加载正常：-/。

当我进行颤振构建网络时 - 页面永远不会加载，重新加载没有帮助。

基本错误： Uncaught ReferenceError: firebase is not defined

这是我在第一次启动时看到的 flutter run -d chrome：

Uncaught ReferenceError: firebase is not defined
    at (index):26
app.js:1 Failed to load resource: the server responded with a status of 404 (Not Found)
require.js:143 Uncaught Error: Script error for "@firebase/app", needed by: dart_sdk
http://requirejs.org/docs/errors.html#scripterror
    at makeError (require.js:168)
    at HTMLScriptElement.onScriptError (require.js:1738)
:57663/favicon.ico:1 Failed to load resource: the server responded with a status of 404 (Not Found)

当我做 flutter build web - 只有这个错误：

Uncaught ReferenceError: firebase is not defined
    at Object.aoq (top_level.dart:80)
    at Object.auD (cloud_firestore_web.dart:33)
    at cloud_firestore_web.dart:26
    at aom.a (async_patch.dart:315)
    at aom.$2 (async_patch.dart:340)
    at Object.G (async_patch.dart:245)
    at Object.UR (main.dart:8)
    at js_helper.dart:3246
    at js_helper.dart:3246
    at dartProgram (js_helper.dart:3246)

我的 index.html 文件：

<!DOCTYPE html>
<html>
<head>
  <meta charset="UTF-8">
  <title>new_flowers</title>
</head>
<body>
  <script src="main.dart.js" type="application/javascript"></script>
  <script src="https://www.gstatic.com/firebasejs/7.15.0/firebase-app.js"></script>
  <script src ="https://www.gstatic.com/firebasejs/7.15.0/firebase-firestore.js"></script>
  <script src="https://www.gstatic.com/firebasejs/7.15.0/firebase-auth.js"></script>
  <script>
  // Your web app's Firebase configuration
  var firebaseConfig = {
    apiKey: "...",
    authDomain: "...",
    databaseURL: "...",
    projectId: "...",
    storageBucket: "...",
    messagingSenderId: "...",
    appId: "...",
    measurementId: "..."
  };

  // Initialize Firebase
  firebase.initializeApp(firebaseConfig);
  </script>
</body>
</html>

【问题讨论】：

标签： firebase flutter

【解决方案1】：

您的 index.html 有点乱。尝试像这样定义你的脚本：

Firebase 应用 + 使用的 CDN
Firebase 应用配置
服务人员
Main.dart.js

编辑：代码格式不正确，这里是 html 代码的链接：`

<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="bevent">
  <link rel="apple-touch-icon" href="icons/Icon-192.png">

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

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

<body>
  <!-- The core Firebase JS SDK is always required and must be listed first -->
  <script src="https://www.gstatic.com/firebasejs/7.15.1/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/7.15.1/firebase-auth.js"></script>
  <script src="https://www.gstatic.com/firebasejs/7.15.1/firebase-firestore.js"></script>
  <script src="https://www.gstatic.com/firebasejs/7.15.2/firebase-storage.js"></script>
  <script src="https://www.gstatic.com/firebasejs/7.15.1/firebase-analytics.js"></script>

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

【讨论】：

您的代码就像魔术一样工作。 Service Worker 的用途是什么？您从哪里获得信息以将其放入？
当你创建一个 Flutter 项目时，它会自动添加。
有什么方法可以在 dart 而不是 HTML 中添加 firebase 配置？
我不这么认为，因为你必须在 dart & flutter 之前加载 firebase sdks
你是一个英雄，完全遵循这些。我的 webappw 在 lcoally 上运行，但在单独发布后，它只是一个带有未定义 firebase 的白屏。这种 JS 条目的方向，使它起作用。