Vim-Vixen/src/content/usecases/FocusUseCase.ts

import FocusPresenter, { FocusPresenterImpl }
  from '../presenters/FocusPresenter';

export default class FocusUseCases {
  private presenter: FocusPresenter;

  constructor({
    presenter = new FocusPresenterImpl(),
  } = {}) {
    this.presenter = presenter;
  }

  focusFirstInput() {
    this.presenter.focusFirstElement();
  }
}