未捕获的类型错误：无法读取未定义的属性“Auth”

Question

我正在尝试使用 firebase API 构建登录页面。在尝试让用户保持登录状态时，下面提到的行 -

firebase.auth.Auth.Persistence.LOCAL; 

出现此错误 -

Uncaught TypeError: Cannot read property 'Auth' of undefined

刚接触这个，无法解决这个问题。更新了 firebase 版本但没有帮助。任何相同的解决方案都会有所帮助。下面是JS文件-

// Initialize Firebase
firebase.initializeApp(firebaseConfig);

//For user to stay logged in during next session
firebase.auth.Auth.Persistence.LOCAL; 

$("#btn-login").click(function(){

var email = $("#email").val();
console.log(email);
var password = $("#password").val(); 
console.log(password);

var result = firebase.auth().signInWithEmailAndPassword(email, password);

result.catch(function(error){
    var errorCode = error.code; 
    var errorMessage = error.message; 

    console.log(errorCode);
    console.log(errorMessage);
});

});