Method focus

src/map-feature.js:727–729

(options)

  //      options (optional): as options parameter for native HTMLElement
  //                          https://developer.mozilla.org/en-US/docs/Web/API/HTMLElement/focus
  focus(options) {
    this._groupEl.focus(options);
  }

  // a method that makes the <g> element lose focus, or invoking the user-defined blur event
  blur() {