1、创建一个react项目
npx create-react-app my-app
2、运行一个react项目
npm start
3、简单的js代码示意
import React from 'react';
import ReactDOM from 'react-dom';
import './index.css';
function Square(props) {
return (
<button className="square" onClick={props.onClick}>
{props.value}
</button>
);
}
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>
);
}
}
class Game extends React.Component {
render() {
return (
<div className="game">
<div className="game-board">
<Board />
</div>
<div className="game-info">
<div>{/* status */}</div>
<ol>{/* TODO */}</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;
}
对react框架的一些基本的理解
A、我认为整个代码,是从board模块的render开始渲染的,将内容渲染到页面上面。
B、整个代码,触发事件是主线,下面是我对触发事件的一下理解。
1、 鼠标点击空白处的按钮标签,这时的button已经被注册好了onclick的触发事件,是通过props传输过来了的
2、render会记得你在哪里点击这个事件,比如说是在1上面触发了
{this.renderSquare(1)}
这样,就会调用renderSquare()方法,这个方法会先执行value = {this.state.squares[i]} 为数组赋值的操作,这个数组用来记录哪个位置已经被赋值了,其次,会进行onClick = {() => this.handleClick(i)} 这个操作,进行数组的复制const squares = this.state.squares.slice();判断是否应该继续游戏 if (calculateWinner(squares) || squares[i]) ,为提示下一步谁进行操作重新渲染squares[i] = this.state.xIsNext ? ‘X’ : ‘O’; 为数组赋值squares: squares,下家的标志取反xIsNext: !this.state.xIsNext,