##目的
Reactの学習のため、下記のチュートリアルプログラムを作成してみる。
https://ja.reactjs.org/tutorial/tutorial.html

##環境
Windows10Home
node v10.16.0
npm 6.9.0

##記述
###create-react-app
テキストエディタを使用するので、ベースとしてcreate-react-appを使用。
下記を実行し土台を作成。

npm

npx create-react-app test
cd test
npm start

その後作成したtest\src配下のファイルを全て削除し、index.css,index.jsを作成。

###cssの記述

index.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;
}

###Reactの記述

index.js

import React from 'react';
import ReactDOM from 'react-dom';
import './index.css';

function Square(props) {
  return (
    <button className="square" 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)}
      />
    );
  }

  render() {
    return (
      <div>
        <div className="board-row">
          {this.renderSquare(0)}
          {this.renderSquare(1)}
          {this.renderSquare(2)}
        </div>
        <div className="board-row">
          {this.renderSquare(3)}
          {this.renderSquare(4)}
          {this.renderSquare(5)}
        </div>
        <div className="board-row">
          {this.renderSquare(6)}
          {this.renderSquare(7)}
          {this.renderSquare(8)}
        </div>
      </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) => {
      const desc = move ?
        'Go to move #' + move :
        'Go to game start';
      return (
        <li key={move}>
          <button onClick={() => this.jumpTo(move)}>{desc}</button>
        </li>
      );
    });

    let status;
    if (winner) {
      status = "Winner: " + winner;
    } else {
      status = "Next player: " + (this.state.xIsNext ? "X" : "O");
    }

    return (
      <div className="game">
        <div className="game-board">
          <Board
            squares={current.squares}
            onClick={i => this.handleClick(i)}
          />
        </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 squares[a];
    }
  }
  return null;
}

##追加課題
###1.履歴内のそれぞれの着手の位置を (col, row) というフォーマットで表示する。
　historyにマスの情報を追加し、値を呼び出せるように変更。

index.js(handleClick)

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,
          col: (i % 3) + 1, //追加
          row: Math.floor(i / 3) + 1,　//追加
        }
      ]),
      stepNumber: history.length,
      xIsNext: !this.state.xIsNext
    });
  }

遷移リストにマスの位置を表示するようにstep.col,step.row追加

index.js(render)

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

    const moves = history.map((step, move) => {
      const desc = move ?
        'Go to move #' + move +'('+ step.col +','+ step.row +')' : //変更
        'Go to game start';
      return (
        <li key={move}>
          <button onClick={() => this.jumpTo(move)}>{desc}</button>
        </li>
      );
    });

###2.着手履歴のリスト中で現在選択されているアイテムをボールドにする。
GameコンポーネントにstepNumberをステートとして保持しているので、これを利用してstepNumberとhistoryのindexの役割をするmoveが一致した際にboldというclassを付与

index.js(render)

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

    const moves = history.map((step, move) => {
      const desc = move ?
        'Go to move #' + move +'('+ step.col +','+ step.row +')' :
        'Go to game start';
      return (
        <li key={move}>
          <button onClick={() => this.jumpTo(move)}
          className={this.state.stepNumber=== move ? 'bold':'' } >{desc}</button>
        </li>
      );
    });

boldclass付与時に太字が有効になるようにcssに追加

index.css

.bold {
  font-weight: bold;
}

###3.Board でマス目を並べる部分を、ハードコーディングではなく 2 つのループを使用するように書き換える。
keyを追加し、map関数を二重で使用する。

index.js(Board)

class Board extends React.Component {
  renderSquare(i) {
    return (
      <Square
        value={this.props.squares[i]}
        onClick={() => this.props.onClick(i)}
        key={i}
      />
    );
  }

  render() {
    return (
      <div>
        {
          Array(3).fill(0).map((row, i) => {
            return (
              <div className="board-row" key={i}>
                {
                  Array(3).fill(0).map((col, j) => {
                    return(
                      this.renderSquare(i * 3 + j)
                    )
                  })
                }
              </div>
            )
          })
        }
      </div>
    );
  }
}

###4.着手履歴のリストを昇順・降順いずれでも並べかえられるよう、トグルボタンを追加する。
Gameコンポーネントに昇順・降順を並べ替えるボタンを追加し、昇順か降順かどうかを保持するstateを新しく定義することで遷移リストをレンダリングする際にstateの状態によって昇順か降順を切り替えを行う。

index.js(Game)

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,
          col: (i % 3) + 1,
          row: Math.floor(i / 3) + 1,
        }
      ]),
      stepNumber: history.length,
      xIsNext: !this.state.xIsNext
    });
  }

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

  toggleAsc() {
     this.setState({
       asc: !this.state.asc,
     });
   }

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

    const moves = history.map((step, move) => {
      const desc = move ?
        'Go to move #' + move +'('+ step.col +','+ step.row +')' :
        'Go to game start';
      return (
        <li key={move}>
          <button onClick={() => this.jumpTo(move)}
          className={this.state.stepNumber=== move ? 'bold':'' } >{desc}</button>
        </li>
      );
    });

    let status;
    if (winner) {
      status = "Winner: " + winner;
    } else {
      status = "Next player: " + (this.state.xIsNext ? "X" : "O");
    }
    return (
      <div className="game">
        <div className="game-board">
          <Board
            squares={current.squares}
            onClick={i => this.handleClick(i)}
          />
        </div>
        <div className="game-info">
          <div>{status}</div>
          <div><button onClick={() => this.toggleAsc()}>{(this.state.asc ? "desc":"asc")}</button></div>
          <ol>{this.state.asc ? moves : moves.reverse()}</ol>
        </div>
      </div>
    );
  }
}

###5.どちらかが勝利した際に、勝利につながった 3 つのマス目をハイライトする。
calculateWinner関数に勝者の判定だけでなくどのマスの列が揃ったかの配列も返すように変更を加える。

index.js(calculateWinner)

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: [a,b,c]
      };
    }
  }
  return null;
}

calculateWinner関数の帰り値を変更したため、Gameコンポーネントの修正とBoardコンポーネントに揃った列のマスを渡すように変更。

index.js(Game)

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,
          col: (i % 3) + 1,
          row: Math.floor(i / 3) + 1,
        }
      ]),
      stepNumber: history.length,
      xIsNext: !this.state.xIsNext
    });
  }

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

  toggleAsc() {
     this.setState({
       asc: !this.state.asc,
     });
   }

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

    const moves = history.map((step, move) => {
      const desc = move ?
        'Go to move #' + move +'('+ step.col +','+ step.row +')' :
        'Go to game start';
      return (
        <li key={move}>
          <button onClick={() => this.jumpTo(move)}
          className={this.state.stepNumber=== move ? 'bold':'' } >{desc}</button>
        </li>
      );
    });

    let status;
    if (settlement) {
      status = "Winner: " + settlement.winner;
    } else {
      status = "Next player: " + (this.state.xIsNext ? "X" : "O");
    }
    return (
      <div className="game">
        <div className="game-board">
          <Board
            squares={current.squares}
            onClick={i => this.handleClick(i)}
            highlightCells={settlement ? settlement.line : []}
          />
        </div>
        <div className="game-info">
          <div>{status}</div>
          <div><button onClick={() => this.toggleAsc()}>{(this.state.asc ? "desc":"asc")}</button></div>
          <ol>{this.state.asc ? moves : moves.reverse()}</ol>
        </div>
      </div>
    );
  }
}

Boardコンポーネントに揃った列のマスの配列を受け取り、マスをレンダリング時に揃ったマスをハイライトするか否をisHighlightで判定。

index.js(Board)

class Board extends React.Component {
  renderSquare(i, isHighlight = false) {
    return (
      <Square
        value={this.props.squares[i]}
        onClick={() => this.props.onClick(i)}
        key={i}
        isHighlight={isHighlight}
      />
    );
  }

  render() {
    return (
      <div>
        {
          Array(3).fill(0).map((row, i) => {
            return (
              <div className="board-row" key={i}>
                {
                  Array(3).fill(0).map((col, j) => {
                    return(
                      this.renderSquare(i * 3 + j, this.props.highlightCells.indexOf(i * 3 + j) !== -1)
                    )
                  })
                }
              </div>
            )
          })
        }
      </div>
    );
  }
}

SquareコンポーネントをisHighlightがtrueのときのみhighlightクラスを付与するように変更。

index.js(Square)

function Square(props) {
  return (
    <button 
    className={`square ${props.isHighlight ? 'highlight' : ''}`} 
    onClick={() => props.onClick()}>
      {props.value}
    </button>
  );
}

最後にhighlightクラスがついたときに背景色が変わるようにcssに追加。

index.css

.highlight {
  background-color: yellow;
}

###6.どちらも勝利しなかった場合、結果が引き分けになったというメッセージを表示する。
calculateWinner関数に引き分けかどうかの情報も渡すように変更。

index.js(calculateWinner

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: [a,b,c],
        isDraw: false
      };
    }
  }
  if(squares.filter((e) => !e).length === 0){
    return {
      isDraw: true,
      winner: null,
      line: []
    }
  }
  return null;
}

Gameコンポーネントのrenderメソッドを書き換えていきます。

index.js(Game)

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,
          col: (i % 3) + 1,
          row: Math.floor(i / 3) + 1,
        }
      ]),
      stepNumber: history.length,
      xIsNext: !this.state.xIsNext
    });
  }

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

  toggleAsc() {
     this.setState({
       asc: !this.state.asc,
     });
   }

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

    const moves = history.map((step, move) => {
      const desc = move ?
        'Go to move #' + move +'('+ step.col +','+ step.row +')' :
        'Go to game start';
      return (
        <li key={move}>
          <button onClick={() => this.jumpTo(move)}
          className={this.state.stepNumber=== move ? 'bold':'' } >{desc}</button>
        </li>
      );
    });

    let status;
    if (settlement) {
      if (settlement.isDraw) {
        status = "Draw";
      }else{
        status = "Winner: " + settlement.winner;
      }
    } else {
      status = "Next player: " + (this.state.xIsNext ? "X" : "O");
    }
    return (
      <div className="game">
        <div className="game-board">
          <Board
            squares={current.squares}
            onClick={i => this.handleClick(i)}
            highlightCells={settlement ? settlement.line : []}
          />
        </div>
        <div className="game-info">
          <div>{status}</div>
          <div><button onClick={() => this.toggleAsc()}>{(this.state.asc ? "desc":"asc")}</button></div>
          <ol>{this.state.asc ? moves : moves.reverse()}</ol>
        </div>
      </div>
    );
  }
}