how to tell on the client side that the user is logged in when using node js and react

I used the following code (https://github.com/firebase/quickstart-nodejs/blob/master/auth-sessions/app.js) to log a user in using React and Nodejs and Firebase. I can tell if someone is logged in using NodeJs, but not on the ReactJs side. I used the code and that does not work after a few minutes:

`app.auth().onAuthStateChanged((user) => {`

首先将 React 客户端 auth 设置与链接的 auth-sessions/app.js 示例进行比较，并检查 app.auth().onAuthStateChanged 回调。确定为什么该回调在几分钟后不再提供预期的登录状态；完成的标准是 React 端能够可靠地识别用户是否已登录。

由索引模型根据 Issue 内容生成。