pinafore/routes/_components/virtualList/VirtualListFooter.html

<div class="virtual-list-footer"
  ref:node
  style="transform: translateY({{$heightWithoutFooter}}px);" >
  <:Component {component} />
</div>
<style>
  .virtual-list-footer {
    position: absolute;
    top: 0;
    width: 100%;
  }
</style>
<script>
  import { virtualListStore } from './virtualListStore'
  import { AsyncLayout } from '../../_utils/AsyncLayout'

  export default {
    oncreate() {
      const asyncLayout = new AsyncLayout(() => '__footer__')
      asyncLayout.observe('__footer__', this.refs.node, (rect) => {
        asyncLayout.disconnect()
        this.store.setForRealm({footerHeight: rect.height})
      })
    },
    store: () => virtualListStore,
  }
</script>