Add className dynamically
Tags: react, javascript, css
Published: 2021-04-23 10:30:36

How to add className dynamically from a class as a parent and function as a child in ReactJS?

I want to add different className to all the winning boxes in my tic tac toe game. I am a newbie to React and so can't figure out how to do it.

Here's codepen link to my code:
https://codepen.io/khushikothari/pen/vYgmoNa 


Also here is the js code:

function Square(props) {
  const className = "square" + (props.highlight ? "highlight" : "");
  return (
    <button className= {className} 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)}
        highlight = {false}
      />
    );
  }

  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;
        const current = history[history.length -1];
        const squares_cpy = current.squares.slice();
        let arr = calculateWinner(squares_cpy);
        if (arr[1] || squares_cpy[i]) {
          return;
        }
        squares_cpy[i] = this.state.xIsNext ? 'X' : 'O';
        this.setState({
          history: history.concat([{
            squares: squares_cpy
          }]),
          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];
        let arr = 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 (arr[1]) {
          status = 'Winner: ' + arr[1];
          
          }
        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 [lines[i], squares[a]];
    }
  }
  return [null, null];
}