Tic Tac Toe

index.html

<div id="errors" style="
  background: #c00;
  color: #fff;
  display: none;
  margin: -20px -20px 20px;
  padding: 20px;
  white-space: pre-wrap;
"></div>
<div id="root"></div>
<script>
window.addEventListener('mousedown', function(e) {
  document.body.classList.add('mouse-navigation');
  document.body.classList.remove('kbd-navigation');
});
window.addEventListener('keydown', function(e) {
  if (e.keyCode === 9) {
    document.body.classList.add('kbd-navigation');
    document.body.classList.remove('mouse-navigation');
  }
});
window.addEventListener('click', function(e) {
  if (e.target.tagName === 'A' && e.target.getAttribute('href') === '#') {
    e.preventDefault();
  }
});
window.onerror = function(message, source, line, col, error) {
  var text = error ? error.stack || error : message + ' (at ' + source + ':' + line + ':' + col + ')';
  errors.textContent += text + '\n';
  errors.style.display = '';
};
console.error = (function(old) {
  return function error() {
    errors.textContent += Array.prototype.slice.call(arguments).join(' ') + '\n';
    errors.style.display = '';
    old.apply(this, arguments);
  }
})(console.error);
</script>

script.babel

function Square(props) {
  return (
    <button className={"square " + (props.highlight ? 'winning' : '')} onClick={props.onClick}>
      {props.value}
    </button>
  );
}

class Board extends React.Component {
  renderSquare(i) {
    return (
      <Square
        value={this.props.squares[i]}
        onClick={() => this.props.onClick(i)}
        highlight={this.props.winLine && this.props.winLine.includes(i)}
      />
    );
  }
  
  render() {
    // Use two loops to make the squares
    const boardSize = 3;
    let squares = [];
    for (let x = 0 ; x < boardSize ; x++) {
      let row = [];
      for (let y = 0 ; y < boardSize ; y++) {
        row.push(this.renderSquare(x * boardSize + y));
      }
      squares.push(<div key={x} className="board-row">{row}</div>);
    }

    return (
      <div>{squares}</div>
    );
  }
}

class Game extends React.Component {
  constructor(props) {
    super(props);
    this.state = {
      history: [
        {
          squares: Array(9).fill(null)
        }
      ],
      stepNumber: 0,
      xIsNext: true
    };
  }

  handleClick(i) {
    const history = this.state.history.slice(0, this.state.stepNumber + 1);
    const current = history[history.length - 1];
    const squares = current.squares.slice();
    
    if (calculateWinner(squares) || squares[i]) {
      return;
    }
    squares[i] = this.state.xIsNext ? "X" : "O";
    this.setState({
      history: history.concat([
        {
          squares: squares
        }
      ]),
      stepNumber: history.length,
      xIsNext: !this.state.xIsNext
    });
  }

  jumpTo(step) {
    this.setState({
      stepNumber: step,
      xIsNext: (step % 2) === 0
    });
  }

  render() {
    const history = this.state.history;
    const current = history[this.state.stepNumber];
    const winner = calculateWinner(current.squares);

    const moves = history.map((step, move) => {
      let positionCol = -1;
      let positionRow = -1;
      let positionMark = null;

      if (move) {
        for(let i = 0 ; i < 9 ; i++) {
          if (history[move].squares[i] != history[move - 1].squares[i]) {
            positionCol = parseInt(i % 3) + 1;
            positionRow = parseInt(i / 3) + 1;
            positionMark = history[move].squares[i];
          }
        }
      }
      
      const desc = move ?
        `Go to move #${move} ${positionMark} (${positionCol},${positionRow})`:
        'Go to game start';
      return (
        <li key={move}>
          <button className={`move ${this.state.stepNumber == move ? 'active' : ''}`} onClick={() => this.jumpTo(move)}>{desc}</button>
        </li>
      );
    });

    let status;
    let winLine;
    if (!winner) {
      status = "Next player: " + (this.state.xIsNext ? "X" : "O");
    } else if (winner === 'draw') {
      status = "The game ended in a draw!";
    } else {
      winLine = winner.line;
      status = "Winner: " + winner['winner'];
    }

    return (
      <div className="game">
        <div className="game-board">
          <Board
            squares={current.squares}
            onClick={i => this.handleClick(i)}
            winLine={winLine}
          />
        </div>
        <div className="game-info">
          <div>{status}</div>
          <ol>{moves}</ol>
        </div>
      </div>
    );
  }
}

// ========================================

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

function calculateWinner(squares) {
  const lines = [
    [0, 1, 2],
    [3, 4, 5],
    [6, 7, 8],
    [0, 3, 6],
    [1, 4, 7],
    [2, 5, 8],
    [0, 4, 8],
    [2, 4, 6]
  ];
  for (let i = 0; i < lines.length; i++) {
    const [a, b, c] = lines[i];
    if (squares[a] && squares[a] === squares[b] && squares[a] === squares[c]) {
      return {
        winner: squares[a],
        line: lines[i]
      }
    }
  }

  for (let i = 0 ; i < squares.length ; i++) {
    if (squares[i] == null) {
      return null;
    }
  }

  return 'draw';
}

scripts

<script src="https://unpkg.com/react@16/umd/react.development.js"></script>
<script src="https://unpkg.com/react-dom@16/umd/react-dom.development.js"></script>

style.css

body {
  font: 14px "Century Gothic", Futura, sans-serif;
  margin: 20px;
}

ol, ul {
  padding-left: 30px;
}

.board-row:after {
  clear: both;
  content: "";
  display: table;
}

.status {
  margin-bottom: 10px;
}

.square {
  background: #fff;
  border: 1px solid #999;
  float: left;
  font-size: 24px;
  font-weight: bold;
  line-height: 34px;
  height: 34px;
  margin-right: -1px;
  margin-top: -1px;
  padding: 0;
  text-align: center;
  width: 34px;
}

.square:focus {
  outline: none;
}

.kbd-navigation .square:focus {
  background: #ddd;
}

.game {
  display: flex;
  flex-direction: row;
}

.game-info {
  margin-left: 20px;
}

.move.active {
  font-weight: bold;
}

.square.winning {
  background-color: lightblue;
}

tic-tac-toe.markdown

Tic Tac Toe

A Pen by Dave Hughes on CodePen.

License.