Part 3 - onScroll update to prevent elastic inertia

Post.js

onScroll = () => {
  const scrollTop = windowScroll.get('top');

  if (scrollTop < 0 && !this.isTransitioningFromDrag) {
    if (this.isTouching) this.isDragging = true;
    if (this.isDragging) {
      if (scrollTop > -DRAG_THRESHOLD) {
        const dragProgress = Math.min(1, -scrollTop / DRAG_LIMIT);
        this.setState({ dragProgress });
      } else {
        this.isTransitioningFromDrag = true;
        this.props.navigateTo('home');
      }
    }
    return;
  }

  this.setState({ dragProgress: 0 });
  this.isDragging = false;
};