Javascript 登录到主页的登录页后未获取firebase用户凭据

我正在尝试使用firebase auth和纯Javascript进行简单的登录和注销，我不确定这是否正确。但我到目前为止所做的是：

index.html

在我的头元素中已经有了所有必要的导入链接（firebase应用程序、firebase auth）

app.js

const db = firebase.firestore();
const auth = firebase.auth();
var user = firebase.auth().currentUser;

function signIn(){
  const email = document.getElementById("email").value;
  const password = document.getElementById("password").value;
  firebase.auth().signInWithEmailAndPassword(email, password)
  .then((userCredential) => {
    // Signed in
    var user = userCredential.user;
    alert("Sign In");
  })
  .catch((error) => {
    var errorCode = error.code;
    var errorMessage = error.message;
    alert(errorMessage);
  });
}

function logOut() {
  // [START auth_sign_out]
  firebase.auth().signOut().then(() => {
    alert("Log out");
  }).catch((error) => {
    // An error happened.
    alert(error);
  });
  // [END auth_sign_out]
}

  //[START auth_state_listener]
  firebase.auth().onAuthStateChanged((user) => {
      if (user) {
        location.replace("home.html");
        document.getElementById("email").innerHTML = user.email  
      } else {
        // User is signed out
        // ...
        location.replace("index.html");
      }
    });

我试图实现的是，当我使用firebase身份验证中已有的电子邮件和密码登录时，我将被重定向到我的

home.html

，它将显示我的电子邮件，如果用户未登录

home.html

将无法访问，并且只显示

index.html

该代码现在的情况是，在我输入电子邮件和密码后，将出现一个循环，其中页面将不断显示

index.html

和

home.html

，并且不会显示电子邮件

<h1 id="email"></h1>
<button onclick="logOut()">Logout</button>
<script src="app.js"></script>

const db = firebase.firestore();
const auth = firebase.auth();
var user = firebase.auth().currentUser;

function signIn(){
  const email = document.getElementById("email").value;
  const password = document.getElementById("password").value;
  firebase.auth().signInWithEmailAndPassword(email, password)
  .then((userCredential) => {
    // Signed in
    var user = userCredential.user;
    alert("Sign In");
  })
  .catch((error) => {
    var errorCode = error.code;
    var errorMessage = error.message;
    alert(errorMessage);
  });
}

function logOut() {
  // [START auth_sign_out]
  firebase.auth().signOut().then(() => {
    alert("Log out");
  }).catch((error) => {
    // An error happened.
    alert(error);
  });
  // [END auth_sign_out]
}

  //[START auth_state_listener]
  firebase.auth().onAuthStateChanged((user) => {
      if (user) {
        location.replace("home.html");
        document.getElementById("email").innerHTML = user.email  
      } else {
        // User is signed out
        // ...
        location.replace("index.html");
      }
    });