Class InView

src/InView.tsx:65–210

 ```
 */
export class InView extends React.Component<
  IntersectionObserverProps | PlainChildrenProps,
  State
> {
  node: Element | null = null;
  _unobserveCb: (() => void) | null = null;
  lastInView: boolean | undefined;

  constructor(props: IntersectionObserverProps | PlainChildrenProps) {
    super(props);
    this.state = {
      inView: !!props.initialInView,
      entry: undefined,
    };
    this.lastInView = props.initialInView;
  }

  componentDidMount() {
    this.unobserve();
    this.observeNode();
  }

  componentDidUpdate(prevProps: IntersectionObserverProps) {
    // If a IntersectionObserver option changed, reinit the observer
    if (
      prevProps.rootMargin !== this.props.rootMargin ||
      prevProps.root !== this.props.root ||
      prevProps.threshold !== this.props.threshold ||
      prevProps.skip !== this.props.skip ||
      prevProps.trackVisibility !== this.props.trackVisibility ||
      prevProps.delay !== this.props.delay
    ) {
      this.unobserve();
      this.observeNode();
    }
  }

  componentWillUnmount() {
    this.unobserve();
  }

  observeNode() {
    if (!this.node || this.props.skip) return;
    const {
      threshold,
      root,
      rootMargin,
      trackVisibility,
      delay,
      fallbackInView,
    } = this.props;

    if (this.lastInView === undefined) {
      this.lastInView = this.props.initialInView;
    }
    this._unobserveCb = observe(
      this.node,
      this.handleChange,