Question

您好，我正在尝试学习反应，只是在网站上关注了这个令人惊叹的tutorial。代码解决方案是here on CodePen

我试图找出一种向用户连续显示3的方式，但是我意识到只对特定字母进行CSS更改。

无论如何，是否需要在calculateWinner函数中执行此操作，还是需要在Square函数的按钮属性中添加一个类，并传递某种布尔值以添加一个类？

平方函数：

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

calculateWinners函数：

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;
}

Answer 1

您可以通过此小更改来实现：

Css添加：

button.square[data-pro="X"] {
color: red;
}

button.square[data-pro="O"] {
  color: green;
}

JS只需将function Square(props)更改为：

 function Square(props) {
  return (
  <button className="square" /* adding this */ data-pro={props.value} onClick={props.onClick}>
    {props.value}
  </button>
 );
}

请参阅示例：

function Square(props) {
  return (
    <button className="square" data-pro={props.value}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;
}

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;
}


/* new css */

button.square[data-pro="X"] {
  color: red;
}

button.square[data-pro="O"] {
  color: green;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/15.1.0/react-dom.min.js"></script>
<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>

Answer 2

简短：如果仅需要标记所有用户选择（不包括CSS）

const styles = {}
if(!! props.value) { // not undefined
  styles.color = props.value === "X" ? 'green': 'red'
}
return (
  <button className="square" onClick={props.onClick} style={styles} >
    {props.value}
  </button>
)

更长时间：如果您想了解有关反应（道具传递）的知识，并仅标记获胜路线

f.e。 calculateWinner可以返回对象：

return {winner: squares[a], match: lines[i]}

及以后的

const result = calculateWinner(this.state.squares);
const winner = result.winner;

将result.match传递给renderSuare并在i存在于“匹配”数组中时添加类

当然两种方法都可以结合使用-做得好吗？

如何在React井字游戏教程中添加颜色？

2 个答案: