当我尝试读取 Firebase 上的数据时，出现“未捕获的 ReferenceError：firebase 未定义”错误

Question

I am getting the error in 43th code line. Where am i doing wrong? Also my database's image here: This is my database

<script type="module">
  import {
    initializeApp
  } from "https://www.gstatic.com/firebasejs/9.4.0/firebase-app.js";
  import {
    getDatabase,
    set,
    ref,
    update
  } from "https://www.gstatic.com/firebasejs/9.4.0/firebase-database.js";
  import {
    getAuth,
    createUserWithEmailAndPassword,
    signInWithEmailAndPassword,
    onAuthStateChanged,
    signOut
  } from "https://www.gstatic.com/firebasejs/9.4.0/firebase-auth.js";
  const firebaseConfig = {
    apiKey: ,
    authDomain: ,
    databaseURL: ,
    projectId: ,
    storageBucket: ,
    messagingSenderId: ,
    appId: ,
    measurementId:
  };
  const app = initializeApp(firebaseConfig);
  const db = getDatabase(app);
  const auth = getAuth();
  const firebaseRef = firebase.database().ref("Users");
  firebaseRef.once("value", function(snapshot) {
    snapshot.forEach(function(element) {
      console.log(element);
    })
  });
</script>

Answer 1

The firebase.database().ref() is the namespaced syntax (used on V8 and before) but you are using Modular SDK (V9+). Try refactoring the code as shown below using ref() and get() functions:

// ...imports
// import { get, ref } from "https://www.gstatic.com/firebasejs/9.4.0/firebase-database.js"

const app = initializeApp(firebaseConfig);
const db = getDatabase(app);
const auth = getAuth(app);

const firebaseRef = ref(db, 'Users');

get(firebaseRef).then((snapshot) => {
  if (snapshot.exists()) {
    console.log(snapshot.val());
  } else {
    console.log("No data available");
  }
}).catch((error) => {
  console.error(error);
});