如何使用Javascript查看Firebase数据库中是否存在目录以避免覆盖数据？

<script src="https://www.gstatic.com/firebasejs/9.0.2/firebase-app.js"></script>
<script src="https://www.gstatic.com/firebasejs/9.0.2/firebase-database.js"></script>

const firebaseConfig = {
  apiKey: "YOUR_API_KEY",
  authDomain: "YOUR_AUTH_DOMAIN",
  projectId: "YOUR_PROJECT_ID",
  storageBucket: "YOUR_STORAGE_BUCKET",
  messagingSenderId: "YOUR_MESSAGING_SENDER_ID",
  appId: "YOUR_APP_ID"
};

firebase.initializeApp(firebaseConfig);

const database = firebase.database();
const directoryRef = database.ref("path/to/directory");

directoryRef.once("value")
  .then((snapshot) => {
    const exists = snapshot.exists();
    if (exists) {
      console.log("目录存在");
    } else {
      console.log("目录不存在");
    }
  })
  .catch((error) => {
    console.error("检查目录时出错：", error);
  });