transitionSnippet.js

  static getDerivedStateFromProps(props, state) {
    const { pathname } = props.location;

    if (!state.lastPathname || pathname !== state.lastPathname) {
      return {
        lastPathname: pathname,
        transitionName: getTransitionName({
          from: state.lastPathname,
          to: pathname,
        });
      };
    }

    return null;
  }