javascript 井字游戏未按预期显示背景色

pw9qyyiw  于 2023-02-11  发布在  Java
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我想实现一个功能的React井字游戏说,在新的React测试版文档网站。该功能是突出显示获胜的方块在董事会上,如果一个球员赢了。经过努力编写代码和调试,以找出问题,我仍然不明白为什么它是行不通的。检查凯文王的文章中的一个类似的问题,但他的方法似乎不适用于我的情况。
刚开始学习React tho,并希望确保我完成这个功能和一些更多,并了解React以及在移动到使更多的项目。
下面是Codepen上代码的链接
代码有点庞大,但我仍然会在这里显示主要组件。

function Square({value, onSquareClick, isWinning}) {

  return (
    <button 
      className={"square " + (isWinning ? "winning-square" : null)} onClick={onSquareClick}>
        {value}
    </button>
  );
}

function Board({xIsNext, squares, onPlay, winningSquares}) {

  function handleClick(i) {
    if (squares[i] || calculateWinner(squares)) {
      return;
    }

    const nextSquares = squares.slice();

    if (xIsNext) {
      nextSquares[i] = "X";
    }

    else {
      nextSquares[i] = "O";
    }

    onPlay(nextSquares);
  }

  var winner = calculateWinner(squares);
  let status;
  let winnerName = winner;

  if (winner) {
    status = " is the winner! " + "at line " + winner.line;
    console.log(winner.line);
  }

  else {
    status = "Next Player - " + (xIsNext ? "X" : "O");
  }
 
  // A dirty trick to do make the Board component render squares in less lines of code.
  // Originally supposed to be 
  const row = [
    [0, 1, 2],
    [3, 4, 5],
    [6, 7, 8]
  ];

  return (
    <>
     <div className="status">
        <span className="winner-name">{winnerName}</span>
        <span className="status-desc">{status}</span>
      </div>

      <div className="board-row"> 
        {row[0].map((index) => <Square value={squares[index]} onSquareClick={() => handleClick(index)} key={index}  isWinning={winningSquares.includes(index)} />)}
      </div>

      <div className="board-row">
        {row[1].map((index) => <Square value={squares[index]} onSquareClick={() => handleClick(index)} key={index}isWinning={winningSquares.includes(index)} />)} 
      </div>

      <div className="board-row">
        {row[2].map((index) => <Square value={squares[index]} onSquareClick={() => handleClick(index)} key={index} isWinning={winningSquares.includes(index)} />)} 
      </div>

      {/*
      
      Changed code below to make it more efficient, cleaner and not hardcoded according to the instruction on the React Framework docs page.
      
      <div className="board-row">
        <Square value={squares[0]} onSquareClick={() => handleClick(0)} />
        <Square value={squares[1]} onSquareClick={() => handleClick(1)} />
        <Square value={squares[2]} onSquareClick={() => handleClick(2)} />
        
      </div>

      <div className="board-row">
        <Square value={squares[3]} onSquareClick={() => handleClick(3)} />
        <Square value={squares[4]} onSquareClick={() => handleClick(4)} />
        <Square value={squares[5]} onSquareClick={() => handleClick(5)} />
      </div>

      <div className="board-row">
        <Square value={squares[6]} onSquareClick={() => handleClick(6)} />
        <Square value={squares[7]} onSquareClick={() => handleClick(7)} />
        <Square value={squares[8]} onSquareClick={() => handleClick(8)} /> 
      </div> */}
    </>
  ); 
}

// Main logic of the game.
// Stores state in the history and also renders the Board component.

export default function Game() {
  const [history, setHistory] = useState([Array(9).fill(null)]);
  const [currentMove, setCurrentMove] = useState(0);
  const xIsNext = currentMove % 2 === 0;
  const currentSquares = history[currentMove];

  function handlePlay(nextSquares) {
    const nextHistory = [...history.slice(0, currentMove + 1), nextSquares];
    setHistory(nextHistory);
    setCurrentMove(nextHistory.length - 1);
  }

  // function jumpTo(nextMove) {
    // setCurrentMove(nextMove);
  // }

  const moves = history.map((squares, move) => {

    let description;
    
    if (move > 0) {
      description = "Move #" + move;
    }

    else {
      description = "You've made no moves.";
    }
    
    return (
      <li key={move}>
        {description}
      </li>
    )
  });

  // Sets the state of the toggle ascending or descending mode of the game moves.
  const [toggleUp, setToggleUp] = useState(true);

  // Function tracks the click and updates state accordingly.

  function changeGameMoves() {

    if (toggleUp) {
      setToggleUp(true);
    }

    setToggleUp(!toggleUp);
  } 

  return (
    <>
      <div className="game">
        <div className="game-board">
          <Board xIsNext={xIsNext} squares={currentSquares} onPlay={handlePlay} winningSquares={winner ? winner.line : []}/>
        </div>

        <div className="game-info">
          <button className="toggle-btn" onClick={changeGameMoves}>
            Toggle Game Moves
          </button>

          <h2>Game Moves</h2>
          <ul id="game-moves">
            {toggleUp ? moves.reverse() : moves}
          </ul>
        </div>
      </div>
    </>
  )
}

function calculateWinner(squares) {

  // These are lines checking for whether the player has played on the indicated lines signifying a win.

  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]
  ];

  // Assigns the values of each line array to a, b and c respectively;
  // i.e. for line 1 which is index 0 in the lines array, 
  // a = 0, b = 1, c = 2
  // After looping, it checks if the value of a, b and c are the same and returns the value of variable a and the line which made the win.

  for (let i = 0; i < lines.length; i++) {
    var [a, b, c] = lines[i];
    if (squares[a] && squares[a] === squares[b] && squares[a] === squares[c]) {

      return {
        player: squares[a],
        line: [a, b, c],
      };
    }
  }
  return null;
}

我试着写一个自定义的解决方案,但没有得到预期的结果,我上网查了查,发现了一个article详细说明如何解决的挑战,但这篇文章是基于旧的React方式的组件使用类。通读代码理解,并试图将相同的过程应用到我自己的代码,但最终遇到了障碍。
该代码应该改变三个方块的背景颜色,使游戏中的胜利。

eit6fx6z

eit6fx6z1#

您面临的问题是calculateWinner函数返回null{ player: "O", line: [0, 3, 4] }形式的JSON,您需要使用optional chaining operator?.)处理空情况。
替换:

winner.line.includes(index)

与:

winner?.line?.includes(index)

每个地方都能解决这个问题。
检查工作演示:

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