Tic Tac Toe - A ReactJS Tutorial

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="container"></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.winning ? 'winning-square' : ''}`} onClick={() => props.onClick()}>
      { props.value }
    </button>
  );
}

class Board extends React.Component {
  
  renderSquare(i, winning) {
    return <Square key={i} value={this.props.squares[i]} onClick={() => this.props.onClick(i)} winning={winning}/>;
  }
  
  render() {
    var rows = [];
    let squares = [];
    for (var row=0; row<3; row++) {
      for (var index=row*3; index<row*3+3; index++) {
        
        let winning = false;
        const winningLine = this.props.winningLine;
        if (winningLine) {
          for (var i=0; i<winningLine.length; i++) {
            if (winningLine[i] == index)
              winning = true;
          }
        }
        
        squares.push(this.renderSquare(index, winning));
      }    
      rows.push(<div key={row} className="board-row">{squares}</div>);
      squares = [];
    }
    
    return <div> {rows} </div>;
    
  }
}

class Game extends React.Component {
  constructor() {
    super();
    this.state = {
      history: [{
        squares: Array(9).fill(null)
      }],
      xIsNext: true,
      stepNumber: 0
    };
  }
  handleClick(i) {
    
    const history = this.state.history;
    
    const newest = history[history.length - 1];
    const newestSquares = newest.squares.slice();
    
    if (calculateWinner(newestSquares) || newestSquares[i]) {
      return;
    }
    
    const current = history[this.state.stepNumber];
    const squares = current.squares.slice();
    
    if (calculateWinner(squares) || squares[i]) {
      return;
    }

    const sign = this.state.xIsNext ? 'X' : '0';
    squares[i] = sign;
    
    this.setState({
      history: history.concat([{
        squares: squares,
        selected: {
          row: i % 3 + 1,
          col: Math.floor(i / 3) + 1,
          sign: sign
        },
      }]),
      xIsNext: !this.state.xIsNext,
      stepNumber: history.length,
    });
    
  }
  
  jumpTo(step) {
    this.setState({
      stepNumber: step,
      xIsNext: (step % 2) ? false : true,
    });  
  }
  
  render() {
    
    const history = this.state.history;
    const stepNumber = this.state.stepNumber;
    const current = history[this.state.stepNumber];
    const winner = calculateWinner(current.squares);
    
    let status;
    let winningLine;
    if (winner) {
      status = 'Winner: ' + winner.sign;
      winningLine = winner.line;
    } else {
      status = 'Next player: ' + (this.state.xIsNext ? 'X' : '0');
    }
    
    const moves = history.map((step, move) => {            
      
      const desc = move ? 
            'Move ' + step.selected.sign + ' (' + step.selected.row + ',' + step.selected.col + ')':
            'Game start';
      
      const currentlySelected = (move == stepNumber);
                                 
      return (
        <li key={move}>
          <a href="#" onClick={() => this.jumpTo(move)} className={currentlySelected ? 'selectedMove' : ''}>
            {desc}
          </a>
        </li>
      );      
    });
    
    return (
      <div className="game">
        <div className="game-board">
          <Board squares={current.squares} winningLine={winningLine} onClick={(i) => this.handleClick(i)} />
        </div>
        <div className="game-info">
          <div>{status}</div>
          <ol>{/* TODO */}</ol>
        </div>
        <ol>{moves}</ol>
      </div>
    );
  }
}

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

ReactDOM.render(
  <Game />,
  document.getElementById('container')
);

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 {
        sign: squares[a],
        line: lines[i]
      }
    }
  }
  return null;
}

scripts

<script src="https://cdnjs.cloudflare.com/ajax/libs/react/0.14.7/react-with-addons.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/0.14.7/react-dom.js"></script>

style.css

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

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

li a.selectedMove {
  font-weight: bold;
}

.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;
}

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

.square:focus {
  outline: none;
}

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

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

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

tic-tac-toe-a-reactjs-tutorial.markdown

Tic Tac Toe - A ReactJS Tutorial

A Pen by Colin Tinney on CodePen.

License.