import {scopeFocus, unscopeFocus} from 'a11y-focus-scope';

document.body.innerHTML = `
  <button id="outer-button">Outer Button</button>

  <div id="container">
    <button id="inner-button">Inner Button</button>
  </div>
`;

var container = document.getElementById('container');
var innerButton = document.getElementById('inner-button');
var outerButton = document.getElementById('outer-button');

scopeFocus(container);
// document.activeElement === container;

innerButton.focus();
// document.activeElement === innerButton;

outerButton.focus();
// document.activeElement === container;

unscopeFocus();
outerButton.focus();
// document.activeElement === outerButton;