I currently have a function that creates a user account. I'd like to be able to add a username field too, but I can't seem to figure out how to update that. I noticed in the Google console, that there is a displayName field that is set to null. I don't know how to change it. This is what I have:

function create(email, password, username) {

    firebase.auth().createUserWithEmailAndPassword(email, password).catch(function(error) {

        $timeout(function() {

            var errorCode = error.code;

            var errorMessage = error.message;

            console.log(errorCode.toUpperCase() + : + errorMessage);

        })

    });

    firebase.auth().onAuthStateChanged(function(user) {

        if (user) {

            $timeout(function() {

                console.log(Success! Account Created!);

                user.displayName = username; /* this doesn't work*/

            });

        } else {}

    });

}