pinafore/routes/_components/VirtualList.html

<div class="virtual-list">
  <!-- <div class="virtual-list-viewport" ref:viewport></div> -->
  {{#each $visibleItems as item @key}}
  <VirtualListItem :component
                   offset="{{item.offset}}"
                   props="{{item.props}}"
                   key="{{item.key}}"
  />
  {{/each}}
</div>
<style>
  .virtual-list {
    position: relative;
  }
</style>
<script>
  import VirtualListItem from './VirtualListItem'
  import { virtualListStore } from '../_utils/virtualListStore'

  const DISTANCE_FROM_BOTTOM_TO_FIRE = 400

  export default {
    oncreate () {
      this.observe('items', (items) => {
        this.store.set({
          items: items
        })
      })

      this.observe('distanceFromBottom', (distanceFromBottom) => {
        //console.log('distanceFromBottom', distanceFromBottom)
        if (distanceFromBottom > 0 && // hack: the first it's reported, it's always 0
            distanceFromBottom <= DISTANCE_FROM_BOTTOM_TO_FIRE) {
          this.fire('scrollToBottom')
        }
      })
    },
    data: () => ({
      component: null
    }),
    store: () => virtualListStore,
    components: {
      VirtualListItem
    },
    computed: {
      distanceFromBottom: ($scrollHeight, $scrollTop, $offsetHeight) => {
        return $scrollHeight - $scrollTop - $offsetHeight
      }
    }
  }
</script>