Study React - 함수형 컴포넌트

함수형 컴포넌트

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

함수형 컴포넌트로 바꿨을 때

• this.props => props
• onClick={() => this.props.onClick()}
  => onClick={props.onClick}
  
  

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.state.squares[i]}
  				onClick={() => this.handleClick(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>
      );
    }
}	

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;
}