我正在嘗試使用一個數組，嘗試在我存儲在云 firestore 上的數組上運行doc.data().includes，doc.data().indexOf該數組是文檔中唯一存在的東西。數據是這樣排列的    0: [email protected]    1: [email protected]    2: [email protected]為了獲取數據，我只是這樣做firebase.firestore().collection('mails').doc('emails').get().then((doc) => {            if (doc.exists) {                console.log(doc.data()); //prints the list of emails in form of array                doc.data().IndexOf(email); //error IndexOf doesn't exist                doc.data().includes(email); //error includesOf doesn't exist            }            else {                console.log('data doesn't exist');            }        });