如何在 React 应用程序中处理 Firebase onAuthStateChanged 并相应地路由用户？

我正在开发一个与 Firebase 集成的 React Web 应用程序，并且我正在尝试对我的用户进行身份验证。我已经设置了路线，以便在用户通过身份验证时显示主页组件，否则显示登录页面。但是，当我的应用程序首次加载时，它会显示登录页面，需要一两秒的时间才能识别用户实际上已通过身份验证，然后切换到主页。它看起来很混乱，我猜我没有很好地或足够快地处理 onAuthStateChanged 。在我的 App 组件中，我订阅了一个 ReactObserver，它会在身份验证状态发生更改时发出信号。我该怎么做才能避免这种奇怪的行为？

My App.js:

import {BrowserRouter, Route} from "react-router-dom";
import Home from "./Home";
import Login from "./Login";
import {loggedIn, firebaseObserver} from "../firebase";
import {useEffect, useState} from "react";

export default function App() {
    const [authenticated, setAuthenticated] = useState(loggedIn())

    useEffect(() => {
        firebaseObserver.subscribe('authStateChanged', data => {
            setAuthenticated(data);
        });
        return () => { firebaseObserver.unsubscribe('authStateChanged'); }
    }, []);

   return <BrowserRouter>
             <Route exact path="/" render={() => (authenticated ? <Home/> : <Login/>)} />
          </BrowserRouter>;
}

My firebase.js:

import firebase from "firebase/app";
import "firebase/auth";
import "firebase/firestore";
import ReactObserver from 'react-event-observer';

const firebaseConfig = {
    apiKey: ...,
    authDomain: ...,
    projectId: ...,
    storageBucket: ...,
    messagingSenderId: ...,
    appId: ...
};
firebase.initializeApp(firebaseConfig);
export const auth = firebase.auth();
export const firestore = firebase.firestore();
export const firebaseObserver = ReactObserver();

auth.onAuthStateChanged(function(user) {
    firebaseObserver.publish("authStateChanged", loggedIn())
});

export function loggedIn() {
    return !!auth.currentUser;
}

对于可能关心的人来说，在身份验证实际加载时添加一个简单的标志解决了我的问题。我还添加了受保护的路线（灵感来自本文 https://dev.to/pprathameshmore/protected-routes-in-react-js-216i我想我现在可以很好地继续我的项目了。

App.js:

import {BrowserRouter, Redirect, Route, Switch} from "react-router-dom";
import Home from "./Home";
import Login from "./Login";
import {PrivateRoute} from "./PrivateRoute";
import {loggedIn, firebaseObserver} from "../firebase";
import {useEffect, useState} from "react";

export default function App() {
    const [authenticated, setAuthenticated] = useState(loggedIn());
    const [isLoading, setIsLoading] = useState(true);

    useEffect(() => {
        firebaseObserver.subscribe('authStateChanged', data => {
            setAuthenticated(data);
            setIsLoading(false);
        });
        return () => { firebaseObserver.unsubscribe('authStateChanged'); }
    }, []);

    return isLoading ? <div/> :
        <BrowserRouter>
            <Switch>
                <Route path="/" exact>
                    <Redirect to={authenticated ? "/home" : "/login"} />
                </Route>
                <PrivateRoute path="/home" exact
                              component={Home}
                              hasAccess={authenticated} />
                <PrivateRoute path="/login" exact
                              component={Login}
                              hasAccess={!authenticated} />
                <Route path="*">
                    <Redirect to={authenticated ? "/home" : "/login"} />
                </Route>
            </Switch>
        </BrowserRouter>;
}