我正在制作一个应用程序，并将其放到网上。但当我启动它时，在chrome中有一个空白屏幕。在chrome中有我的控制台日志：
Installed new service worker.
zone.dart:1339 Uncaught ReferenceError: firebase is not defined
at Object.ad5 (core.dart:54)
at Object.ajF (cloud_firestore_web.dart:36)
at cloud_firestore_web.dart:29
at ad0.a (async_patch.dart:316)
at ad0.$2 (async_patch.dart:341)
at Object.U (async_patch.dart:246)
at adP (main.dart:10)
at js_helper.dart:2684
at js_helper.dart:2684
at dartProgram (js_helper.dart:2684)
这是我的主要艺术文件：
import 'package:brew_crew/screens/wrapper.dart';
import 'package:brew_crew/services/auth.dart';
import 'package:flutter/material.dart';
import 'package:firebase_core/firebase_core.dart';
import 'package:provider/provider.dart';
import 'package:brew_crew/models/user.dart';
void main() async {
WidgetsFlutterBinding.ensureInitialized();
await Firebase.initializeApp();
runApp(MyApp());
}
class MyApp extends StatelessWidget {
// This widget is the root of your application.
@override
Widget build(BuildContext context) {
return StreamProvider<UserClass>.value(
value: AuthService().user,
child: MaterialApp(
home: Wrapper(),
),
);
}
}
还有一个index.html文件
<!DOCTYPE html>
<html>
<head>
<!--
If you are serving your web app in a path other than the root, change the
href value below to reflect the base path you are serving from.
The path provided below has to start and end with a slash "/" in order for
it to work correctly.
For more details:
* https://developer.mozilla.org/en-US/docs/Web/HTML/Element/base
-->
<base href="/">
<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="brew_crew">
<link rel="apple-touch-icon" href="icons/Icon-192.png">
<title>brew_crew</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 -->
<script>
var serviceWorkerVersion = null;
var scriptLoaded = false;
function loadMainDartJs() {
if (scriptLoaded) {
return;
}
scriptLoaded = true;
var scriptTag = document.createElement('script');
scriptTag.src = 'main.dart.js';
scriptTag.type = 'application/javascript';
document.body.append(scriptTag);
}
if ('serviceWorker' in navigator) {
// Service workers are supported. Use them.
window.addEventListener('load', function () {
// Wait for registration to finish before dropping the <script> tag.
// Otherwise, the browser will load the script multiple times,
// potentially different versions.
var serviceWorkerUrl = 'flutter_service_worker.js?v=' + serviceWorkerVersion;
navigator.serviceWorker.register(serviceWorkerUrl)
.then((reg) => {
function waitForActivation(serviceWorker) {
serviceWorker.addEventListener('statechange', () => {
if (serviceWorker.state == 'activated') {
console.log('Installed new service worker.');
loadMainDartJs();
}
});
}
if (!reg.active && (reg.installing || reg.waiting)) {
// No active web worker and we have installed or are installing
// one for the first time. Simply wait for it to activate.
waitForActivation(reg.installing ?? reg.waiting);
} else if (!reg.active.scriptURL.endsWith(serviceWorkerVersion)) {
// When the app updates the serviceWorkerVersion changes, so we
// need to ask the service worker to update.
console.log('New service worker available.');
reg.update();
waitForActivation(reg.installing);
} else {
// Existing service worker is still good.
console.log('Loading app from service worker.');
loadMainDartJs();
}
});
// If service worker doesn't succeed in a reasonable amount of time,
// fallback to plaint <script> tag.
setTimeout(() => {
if (!scriptLoaded) {
console.warn(
'Failed to load app from service worker. Falling back to plain <script> tag.',
);
loadMainDartJs();
}
}, 4000);
});
} else {
// Service workers not supported. Just drop the <script> tag.
loadMainDartJs();
}
</script>
</body>
</html>
此外，如果需要，您可以转到git存储库中的另一个文件。https://github.com/rostikro/The-app
我使用的是Flutter 2.0.2。
我查看了你的Github repo链接，你的index.html缺少Firebase JS条目的实现。
您的pubspec.yaml文件包括以下依赖项：
firebase_core: ^0.7.0
firebase_auth: ^0.20.1
cloud_firestore: ^0.16.0+1
但你并没有告诉你的index.html导入它们。以下导入将适用于firebase_auth和cloud_firestore 的^1.0.1版本
<script src="https://www.gstatic.com/firebasejs/7.20.0/firebase-firestore.js"></script>
<script src="https://www.gstatic.com/firebasejs/7.20.0/firebase-app.js"></script>
<script src="https://www.gstatic.com/firebasejs/7.20.0/firebase-auth.js"></script>
请遵循文档，他们对Firebase&这里特别提到Flutter。您还提到您使用的是Flutter 2.0.2版本，因此请注意零安全。