Insert username in signup firebase

I’m writing a code but I need to save into firebase the username of the user . So I did this :
> Signup(email: string, password: string, displayNmae: string) {
> this.angFire.auth.createUser({
> email: email,
> password: password
> }).catch(
> (err) => {
> console.log(err);
> this.error = err;
> })
> …

Now I have the string displayName, but I’m not able to insert it into the phase of createUser() . How to do it?
I did this

let user1 = firebase.auth().currentUser;
if (user1 != null) { }
user1.updateProfile({
displayName: this.displayName,
photoURL: “https://example.com/jane-q-user/profile.jpg
}).then(function() {
console.log(“Nome utente inserito”);
}, function(error) {
console.log(“Errore durante inserimento utente”);
});

But nothing to do

displayNmae != displayName

I did it but nothing to do :

Cannot read property ‘updateProfile’ of null