in-viewport-8.js

_bindListeners(context=null, event=null) {
  Ember.assert('You must pass a valid context to _bindListeners', context);
  Ember.assert('You must pass a valid event to _bindListeners', event);

  const elementId = get(this, 'elementId');

  Ember.warn('No elementId was found on this Object, `viewportSpy` will' +
    'not work as expected', elementId);

  $(context).on(`${event}#${elementId}`, () => {
    this._scrollHandler(context);
  });
},