🎈 原创

这几天又想折腾自己的破博客了，下了个主题，源代码文件夹里一看全是React，笑死，根本看不懂。

怎么办？硬着头皮学呗。而且本来也计划要学一下前端的框架的。

假期里学了html css js，但是实际开发中用这些效率实在是太低了，非常容易出问题不说，出了问题根本没法改，代码结构太乱了，一万个人一万种写法。所以前端也发展出了自己的框架，目前主流的就是vue react angular。本来是想学vue的，因为vue是比较新的，最近这几年特别火，中国的大部分公司前端都是用vue的，而且这语言本身就是中国人写的。

但是当时想学的时候看了半天看不明白，跑去学JavaScript基础了，现在倒是对React挺感兴趣的了。

跟着React官网教程做的TicTacToe，做倒是做出来了，就是代码看着还是有点逻辑混乱，毕竟没接触过这种框架式的前端开发，有点看不明白。

---

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;
  }
  

index.js

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


// class Square extends React.Component {

//     render() {
//         return (
//             <button
//                 className="square"
//                 onClick={() => { this.props.onClick() }}
//             >
//                 {this.props.value}
//             </button>
//         );
//     }
// }

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

class Board extends React.Component {

    // constructor(props) {
    //     super(props);
    //     this.state = {
    //         squares: Array(9).fill(null),
    //         xIsNext: true,
    //     };
    // }

    // handleClick(i) {
    //     const squares = this.state.squares.slice();
    //     if(calculateWinner(squares) || squares[i])
    //         return;
    //     squares[i] = this.state.xIsNext ? 'X' : 'O';
    //     this.setState({ 
    //         squares: squares,
    //         xIsNext: !this.state.xIsNext, 
    //     });
    // }

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

    render() {
        // const winner = calculateWinner(this.state.squares);
        // let status;
        // if(winner)
        //     status = 'Winner: ' + winner;
        // else
        //     status = 'Next player: ' + (this.state.xIsNext ? 'X' : 'O');

        return (
            <div>
                {/* <div className="status">{status}</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>
    );
  }
}


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;
  }



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

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