Username of logged in keycloak user in angular

how can I find out the username of the user, that logged in via keycoak in angular

constructor(
    appConfig: AppConfigService,
    public rest: RestService,
    private ip: IpServiceService,
    private keycloakService: KeycloakService
  ) {
...
this.keycloakService
            .isLoggedIn()
            .then( loggedIn => {
                if( loggedIn ) {
                    console.log(this.keycloakService.getUsername().toString());
                } else {
                  console.log("User not logged in");
                }
            })
            .catch( reason => console.log ( reason ));

I tried the code above, but it doesn't work