react tutorialをtypescriptで書いてみた

ReactとTypescriptの勉強がてら、React Tutorial （https://ja.reactjs.org/tutorial/tutorial.html ) をTypescriptで実行できるようにしてみました。　

- github: https://github.com/dai-a/react_typescript_tictoctoe

# 実行方法

```
git clone git@github.com:dai-a/react_typescript_tictoctoe.git
cd react_typescript_tictoctoe
bash env.sh
cd ./react-tictoctoe
npm start
```


# メインのコード（App.tsx）

```typescript

import React from "react";
import "./App.css";

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

interface Props {
  squares: string[];
  onClick: any;
}

class Board extends React.Component<Props> {
  renderSquare(i: number) {
    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>
    );
  }
}
interface Props_game {
  history: { squares: string[] }[];
  stepNumber: number;
  xIsNext: boolean;
}

export default class App extends React.Component<{}, Props_game> {
  constructor(props: Props_game) {
    super(props);
    this.state = {
      history: [
        {
          squares: Array(9).fill(null),
        },
      ],
      stepNumber: 0,
      xIsNext: true,
    };
  }

  handleClick(i: number) {
    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: number) {
    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: number) => 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: string[]) {
  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;
}
```

# 感想
- ほとんどReact Tutorialから変えていないけど、多少は勉強になったきがしますが、onClickの型や、`export default class App extends React.Component<{}, Props_game> {` の型部分が理解しきれてませんでした。。。　また、型を作る恩恵がそれほどわからなかったという本末転倒なことが起きていますorz