<button class="e-btn e-btn-primary" type="button" id="opener">
  Open Popup
</button>
<div id="content">
  <p>Content of the custom popup.</p>
  <div class="e-popup-panel__footer">
    <div class="e-popup-panel__actions">
      <button class="e-btn e-btn-primary e-popup-panel__action" type="button">
        Close
      </button>
    </div>
  </div>
</div>

<button class="e-btn e-btn-primary" type="button" id="opener">
  Open Popup
</button>
<div id="content">
  <p>Content of the custom popup.</p>
  <div class="e-popup-panel__footer">
    <div class="e-popup-panel__actions">
      <button class="e-btn e-btn-primary e-popup-panel__action" type="button">
        Close
      </button>
    </div>
  </div>
</div>

document.getElementById('content').querySelector('button').addEventListener('click', () => popup.close());
document.getElementById('opener').addEventListener('click', () => popup.toggle());

const popup = window.e.utils.createPopup(
  document.getElementById('opener'),
  document.getElementById('content'),
  {
    closeOnOutsideClick: false,
    closeOnOEscPress: false,
    placement: 'right',
    elementToFocusOnOpen: document.getElementById('content').querySelector('button')
  }
);

<button class="e-btn e-btn-primary" type="button" id="opener">
  Open Popup
</button>
<div id="content">
  <p>Content of the custom popup.</p>
  <div class="e-popup-panel__footer">
    <div class="e-popup-panel__actions">
      <button class="e-btn e-btn-primary e-popup-panel__action" type="button">
        Close
      </button>
    </div>
  </div>
</div>

<button class="e-btn e-btn-primary" type="button" id="opener">
  Open Popup
</button>
<div id="content">
  <p>Content of the custom popup.</p>
  <div class="e-popup-panel__footer">
    <div class="e-popup-panel__actions">
      <button class="e-btn e-btn-primary e-popup-panel__action" type="button">
        Close
      </button>
    </div>
  </div>
</div>

document.getElementById('content').querySelector('button').addEventListener('click', () => popup.close());
document.getElementById('opener').addEventListener('click', () => popup.toggle());

const popup = window.e.utils.createPopup(
  document.getElementById('opener'),
  document.getElementById('content'),
  {
    closeOnOutsideClick: false,
    closeOnOEscPress: false,
    placement: 'right',
    elementToFocusOnOpen: document.getElementById('content').querySelector('button'),
    type: 'success'
  }
);