const [x, y] = [square[0], square[1]];
if ((color == 'w' && x != 7) || (color == 'b' && x != 0)) return null;
const selectedPiece = this.board[x][y][1];
const [x, y] = [square[0], square[1]];
if ((color == 'w' && x != 7) || (color == 'b' && x != 0)) return null;
const selectedPiece = this.board[x][y][1];