Firebase getIdToken 不起作用

Question

I'm makeing tests with Firebase Authentication from javascript client and I'm trying to retrieve the idToken with retrieve id tokens on clients documentation

I think I'm forgetting something basic.

A user is logged in with Google

The code is just i've seen in other posts and in the documentation. And the result is in the comments.

firebase.auth().onAuthStateChanged(function(user) {
  if (user) {
     console.log(user); // this is shown. Firebase user and provider data
     console.log(user.uid); // Shown
        firebase.auth().user.getIdToken().then(function(idToken) {
           console.log(idToken+'--'); // Nothing happens. No errors and the function not continues
        });
     console.log(user.uid); // Nothing happens
  }
})

Thanks

EDIT:

if I add anything wrong nothing happens too. for example if I add an alert it shows the alert but if I have a mistake, for example alter() not shows any error. Added catch and nothing too

firebase.auth().onAuthStateChanged(function(user) {
  if (user) {
     alter() // Nothing happens and the function stop         
     console.log(user); // this is shown. Firebase user and provider data
     console.log(user.uid); // Shown
        firebase.auth().user.getIdToken().then(function(idToken) {
           console.log(idToken+'--'); // Nothing happens. No errors and the function not continues
        }).catch(function(error) {
            console.log(error+'--'); // Nothing
        });
     console.log(user.uid); // Nothing happens
  }
})

Answer 1

firebase.auth().user doesn't have the user in that moment yet. You have to use the user from firebase.auth().onAuthStateChanged directly like this:

firebase.auth().onAuthStateChanged(function(user) {
    if (user) {
        console.log(user); // It shows the Firebase user
        console.log(firebase.auth().user); // It is still undefined
        user.getIdToken().then(function(idToken) {  // <------ Check this line
           console.log(idToken); // It shows the Firebase token now
        });
    }
});

You can only use firebase.auth().user after firebase.auth().onAuthStateChanged is completed and outside of its scope, otherwise it will be undefined.

Answer 2

firebase.auth().currentUser is synchronous. We can make it asynchronous by subscribing to the auth observable instead.

Depending on the library we're using, the JavaScript SDK has onAuthStateChanged() and AngularFire2 has both authState() onAuthStateChanged().

// For AngularFire:

private afAuth: AngularFireAuth,

afAuth.authState.subscribe(user => {
  if (user) {
    user.getIdToken(true).then(idToken => {
      // ...
    });
  }
});

// or

this.afAuth.auth.onAuthStateChanged(user => {
  if (user) {
    user.getIdToken(true).then(idToken => {
     //...
    });
  }
});



// For the JS SDK
firebase.auth().onAuthStateChanged(user => {
  if (user) {
    user.getIdToken(true).then(idToken => {
      // ...
    });
  }
});