我试过在/dashboard上使用useEffect来检查用户是否登录，但它在将用户重定向回/login页面之前显示 Jmeter 板消息。
/dashboard

function Dashboard() {
    return (
        <div>
            This is Dashboard page.
        </div>
    );

}

export default Dashboard;

/login

const login = (e) => {
        e.preventDefault();
        Axios.post('http://localhost:3001/login', {
            username: username,
            password: password,
        }).then((response) => {
            if (response.data.message) {
                setLoginStatus(response.data.message)
            } else {
                setLoginStatus(response.data[0].username)
            }
        });
    };

    useEffect(() => {
        Axios.get("http://localhost:3001/login").then((response) => {
            if (response.data.loggedIn === true) {
                setLoginStatus(response.data.user[0].username);
                history.push("/dashboard");
            }
        })
    }, [])

server.js

app.get("/login", (req, res) => {
    if (req.session.user) {
        res.send({ loggedIn: true, user: req.session.user })
    } else {
        res.send({ loggedIn: false })
    }
})

app.post("/login", (req, res) => {

    const username = req.body.username;
    const password = req.body.password;

    db.query("SELECT * FROM user WHERE username = ?;", [username],
        (err, result) => {
            if (err) {
                res.send({ err: err });
            }

            if (result.length > 0) {
                bcrypt.compare(password, result[0].password, (err, response) => {
                    if (response) {
                        req.session.user = result;
                        console.log(req.session.user)
                        res.send(result)
                    } else {
                        res.send({ message: "Wrong username/password!" });
                    }
                })
            } else {
                res.send({ message: "User doesn't exist" });
            }
        }
    );
});