React官方教程三子棋游戏(Tic Tac Toe)改进完善

React Tic Tac Toe 教程地址

改进内容：

1. 在游戏历史记录列表显示每一步棋的坐标，格式为 (列号, 行号)。
2. 在历史记录列表中加粗显示当前选择的项目。
3. 使用两个循环来渲染出棋盘的格子，而不是在代码里写死（hardcode）。
4. 添加一个可以升序或降序显示历史记录的按钮。
5. 每当有人获胜时，高亮显示连成一线的 3 颗棋子。
6. 当无人获胜时，显示一个平局的消息。

最终效果：

• 坐标，加粗当前，循环，获胜高亮
  
• 历史记录升降
  
• 平局
  

---

实现代码 - codepen预览

Javascript:

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

function Square(props) {
    return (
        <button
            className={ props.winner ? 'square gold' : 'square' }
            onClick={props.onClick}
        >
            {props.value}
        </button>
    );
}

class Board extends React.Component {

    isWinnerSquare(i) {
        if(this.props.winner && this.props.winner.line.findIndex(el => el === i) !== -1) {
            return true;
        }
        return null;
    }

    renderSquare(i) {
        return (
            <Square
                value={this.props.squares[i]}
                onClick={() => this.props.onClick(i)}
                winner={this.isWinnerSquare(i)}
                key={i}
            />
        );
    }

    render() {
        return (
            <div className="board">
                <div className="row-counters">
                    <div className="row-num">1</div>
                    <div className="row-num">2</div>
                    <div className="row-num">3</div>
                </div>
                {
                    Array(3).fill(null).map((row, x) => {
                        return (
                            <div className="board-row" key={x} >
                                {
                                    Array(3).fill(null).map((square, y) => this.renderSquare(3 * x + y))
                                }
                            </div>
                        )
                    })
                }
                <div className="column-counters">
                    <div className="column-num">a</div>
                    <div className="column-num">b</div>
                    <div className="column-num">c</div>
                </div>
            </div>
        );
    }
}

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

    handleClick(i) {
        const history = this.state.history.slice(0, this.state.stepNumber + 1);
        const current = history[history.length - 1];
        const squares = current.squares.slice();

        const position = getPosition(i);

        // 当有玩家胜出时，或者某个 Square 已经被填充时，该函数不做任何处理直接返回。
        if (caculateWinner(squares) || squares[i]) {
            return;
        }

        squares[i] = this.state.XIsNext ? 'X' : 'O';
        this.setState({ 
            history: history.concat([{
                squares,
                position,
            }]),
            XIsNext: !this.state.XIsNext,
            stepNumber: history.length,
        });
    }

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

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

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

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

        let movesView = this.state.historyReverse ? moves.reverse() : moves;
        
        let status;
        if (winner) {
            status = 'Winner: ' + winner.name;
        } else if(this.state.stepNumber === 9) {
            status = `Draw!`;
        } else {
            status = `Next player: ${ this.state.XIsNext ? 'X' : 'O'}`;
        }
        // console.log(history)

        return (
            <div className="game">
                <div className="game-board">
                    <Board 
                        squares = {current.squares}
                        winner = {winner}
                        onClick = {(i) => this.handleClick(i)}
                    />
                </div>
                <div className="game-info">
                    <div>{status}</div>
                    <div>
                        <button onClick={() => this.historyReverse()}>Reverse</button>
                    </div>
                    <ul>{movesView}</ul>
                </div>
            </div>
        );
    }
}

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

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

// 传入长度为 9 的数组，此函数将判断出获胜者，并根据情况返回 “X”，“O” 或 “null”。
function caculateWinner(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 {
                name: squares[a],
                line: lines[i],
            };
        }
    }
    return null;
}

function getPosition(i) {
    const rowMap = [
        ['a', 3], ['b', 3], ['c', 3],
        ['a', 2], ['b', 2], ['c', 2],
        ['a', 1], ['b', 1], ['c', 1],
    ]
    return rowMap[i];
}

css:

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

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

.board{
    counter-reset: row;
    position: relative;
    padding-left: 34px;
}
.board-row:after {
    clear: both;
    content: "";
    display: table;
}

.row-counters {
    display: flex;
    flex-flow: column-reverse nowrap;
    position: absolute;
    left: 0;
    top: 0;
}
.row-num {
    width: 34px;
    height: 34px;
    font-size: 20px;
    /* font-weight: bold; */
    line-height: 34px;
    padding: 0;
    text-align: center;
}
.column-counters {
    display: flex;
}
.column-num {
    width: 34px;
    height: 34px;
    font-size: 20px;
    /* font-weight: bold; */
    line-height: 34px;
    padding: 0;
    text-align: center;
}

.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;
}

.bold {
    font-weight: bold;
}
.bold button {
    font-weight: bold;
}
.gold {
    background: gold;
}