Как отобразить элемент в матрице в реакции?

class App extends React.Component {
  state = {
    board: [[0, 2, 3, 0], [2, 2, 1, 0], [0, 0, 0, 0]]
  };

  render() {
    const { board } = this.state;

    return (
      <div>
        {board.map((row, i) => (
          <div key = {i}>
            {row.map((col, j) => (
              <span key = {j}>{col}</span>
            ))}
          </div>
        ))}
      </div>
    );
  }
}

ReactDOM.render(<App />, document.getElementById("root"));

<script src = "https://cdnjs.cloudflare.com/ajax/libs/react/16.6.3/umd/react.production.min.js"></script>
<script src = "https://cdnjs.cloudflare.com/ajax/libs/react-dom/16.6.3/umd/react-dom.production.min.js"></script>

<div id = "root"></div>