Javascript 如何为刚创建的用户获取uId

所以，如果我创建了一个新用户，我如何获取它的uId并将其存储在变量中？例如，下面我创建了一个用户，我需要它的新创建的uId，这样我就可以在数据库中创建一个与uId键相同的对象

firebase.auth().createUserWithEmailAndPassword(email, "test123")
    .then(function(user) {
    })
    .catch(function(error) {
      // Handle Errors here.
      var errorCode = error.code;
      var errorMessage = error.message;
      // ...
    });

    firebase.auth().onAuthStateChanged(firebaseUser =>{
      var user = firebase.auth().currentUser;
      key = firebase.database().ref().child('users/' + user.uid);
    });

    startDate = startDate.toString();
    firebase.database().ref('Users/' + key).set({
      employeeId: key,
      Email: email,
      name: name,
      startDate: startDate,
      fcmToken: "",
      Availability: avi,
      Privilege: p
    });

---

在用户创建后添加实时侦听器，如：

firebase.auth().createUserWithEmailAndPassword(email, "test123")
    .then(function(user) {
    })
    .catch(function(error) {
      // Handle Errors here.
      var errorCode = error.code;
      var errorMessage = error.message;
      // ...
    });

    firebase.auth().onAuthStateChanged(firebaseUser =>{

     var ref = firebase.database().ref().child('users/' + firebaseUser.uid);
     //set something
     ref.set({/*save something to a specific uid*/});

    });

---

在用户创建后添加实时侦听器，如：

firebase.auth().createUserWithEmailAndPassword(email, "test123")
    .then(function(user) {
    })
    .catch(function(error) {
      // Handle Errors here.
      var errorCode = error.code;
      var errorMessage = error.message;
      // ...
    });

    firebase.auth().onAuthStateChanged(firebaseUser =>{

     var ref = firebase.database().ref().child('users/' + firebaseUser.uid);
     //set something
     ref.set({/*save something to a specific uid*/});

    });