listenNextLevelButton method

void listenNextLevelButton ()

Listens to the 'next level button' click events, increases the _activeLevel and redirects the user to the 'levelOverview' if the new level is available.

Implementation 

void listenNextLevelButton() {
  querySelector("#button_next_level").onClick.listen((MouseEvent e) {
    this.setActiveLevel(this._activeLevel + 1);
    if (this._activeLevel > this._nrAvailableLevels) {
      this.showNoSuchLevel(this._activeLevel);
    } else {
      this.showLevelOverview();
    }
  });
}