问firebase js sdk查询快照返回空或错误。

EN

<!-- index.html -->

<script src="../lib/jquery_360/jquery360.min.js"></script>
<script src="../lib/bootstrap_5/js/bootstrap.bundle.min.js"></script>

<!-- <script src="../lib/firebase/firebase.min.js"></script> -->
<script src="../lib/firebase/firebase-app.min.js"></script> 
<script src="../lib/firebase/firebase-auth.min.js"></script>
<script src="../lib/firebase/firebase-database.min.js"></script>    

<script src="../script/modal.js"></script>
<script src="../script/utility.js"></script>

<script src="../script/customer.js"></script>

<title>customer</title>

// index.js - jquery onload function

const firebaseApp = firebase.initializeApp({
    // keys here...
});

auth = firebase.auth(); 
db = firebase.database(); 

firebase.auth().onAuthStateChanged((user) => {
    if (user) {
        var uid = user.uid;
        console.log('user logged in!');     
        
        $('#login_popup').modal('hide');
        Clear_Popup_Message('login_popup_msg_box', null); 
    
        GetAllData();         
    } else {
        console.log('user not logged in!');
    }
  });

// GetAllData()

db.ref('menus').orderByChild('list_order').on('value', (snapshot) => {
            prj.configs.menu = snapshot.val();  
});