pinafore/routes/_components/VirtualListItem.html

<div class="virtual-list-item"
     ref:node
     style="transform: translate3d(0, {{offset}}px, 0);"
>
  <:Component {component} virtualProps="{{props}}" />
</div>
<style>
  .virtual-list-item {
    position: absolute;
    top: 0;
  }
</style>
<script>
  import { virtualListStore } from '../_utils/virtualListStore'

  export default {
    oncreate() {
      let itemHeights = this.store.get('itemHeights')
      let key = this.get('key')
      itemHeights[key] = this.refs.node.offsetHeight
      this.store.set({
        itemHeights: itemHeights
      })
    },
    store: () => virtualListStore
  }
</script>