redo.js

class Game extends Compoent {
...  
  redo = () => {
    const { history } = this.state;
    let { historyOffSet } = this.state;
    if (history.size) {
      historyOffSet = Math.min(history.size - 1, historyOffSet + 1);
      const board = history.get(historyOffSet);
      this.setState({ board, historyOffSet });
    }
  };

  undo = () => {
    const { history } = this.state;
    let { historyOffSet, board } = this.state;
    if (history.size) {
      historyOffSet = Math.max(0, historyOffSet - 1);
      board = history.get(historyOffSet);
      this.setState({ board, historyOffSet, history });
    }
  };
...
}