我正在尝试从 firebase 获取数据，但它在应用程序加载时返回空值，但如果我在该文件上编辑某些内容，即使是注释行，那么数据也会加载并且应用程序会运行，我希望当应用程序打开时，所有数据都应该来自 firebase 以运行应用程序。以及如何以相反的顺序排列“grabbedData”，尝试了 grabbedData.reverse()，但没有用。

  const Getdata = async () => {
    let grabbedData = [];

    await firebase
      .database()
      .ref(`/users/`)
      .orderByKey()
      .on("value", (snapshot, key) => {
        // console.log("snapshot....", snapshot);
        grabbedData.push(snapshot.val());
      });
    setUserdata(grabbedData);
    console.log("grabbedData", grabbedData); // empty value here :(
    if (grabbedData) {
      let getfranchiseuid = "";
      Object.keys(grabbedData).map(function (key) {
        let y = grabbedData[key];
        Object.keys(y).map(function (key2) {
          let x = y[key2];
          if (key2 === uid) {
            getfranchiseuid = x.franchiseuid;
          }
        });
      });

      if (getfranchiseuid) {
        let customerList1 = [];
        firebase
          .database()
          .ref(`/serviceProvider/${getfranchiseuid}/franchise/customers`)
          .orderByKey()
          .on("value", (snapshot) => {
            customerList1.push(snapshot.val());
          });
        setCustomerList(customerList1);
        console.log("customerList1customerList1", customerList1);
      }
    }
  };

  useEffect(() => {
    var unsubscribe = firebase.auth().onAuthStateChanged(function (user) {
      if (user) {
        storeUser({ user });
        setUser(user);
        setEmail(user.email);
        setUid(user.uid);
      } else {
        // No user is signed in.
      }
    });
    unsubscribe();
    Getdata();
  }, []);