marshallds

class Component extends React.Component {
  onScroll(event) {
    this.scrollPosition = getScrollPosition(event);
    if (this.scrolling) return;
    this.scrolling = true;
    
    const processLongOperation = (beginPosition) => {
      longOperation(beginPosition, (completionState) => {
        this.setState(completionState, () => {
          //rendered