virt2/assets/vendor_components/popper/packages/test-utils/utils/customEventPolyfill.js

(function() {
  if (typeof window.CustomEvent === 'function') {
    return false;
  }

  function CustomEvent(event, params) {
    params = params || { bubbles: false, cancelable: false, detail: undefined };
    const evt = document.createEvent('CustomEvent');
    evt.initCustomEvent(
      event,
      params.bubbles,
      params.cancelable,
      params.detail
    );
    return evt;
  }

  CustomEvent.prototype = window.Event.prototype;

  window.CustomEvent = CustomEvent;
})();