React 三连棋后续完善
React 三连棋后续完善
React官方文档入门教程中的三连棋,根据文档提供改进建议完善游戏功能。
改进功能:
- 在游戏历史记录列表显示每一步棋的坐标,格式为 (列号, 行号)。
- 在历史记录列表中加粗显示当前选择的项目。
- 使用两个循环来渲染出棋盘的格子,而不是在代码里写死(hardcode)。
- 添加一个可以升序或降序显示历史记录的按钮。
- 每当有人获胜时,高亮显示连成一线的 3 颗棋子。
- 当无人获胜时,显示一个平局的消息。
直接贴上代码:
index.js
import React from 'react'
import ReactDOM from 'react-dom'
import './index.css'
class Square extends React.Component {
render() {
return (
<button
className="square"
onClick={() => this.props.onClick()}>
{this.props.value}
</button>
);
}
}
class Board extends React.Component {
renderSquare(i) {
return <Square
key={i}
value={this.props.squares[i]}
onClick={() => this.props.onClick(i)}
/>;
}
render() {
return (
<div>
{
Array(3).fill(null).map((itemx,x) => (
<div className="board-row" key={x}>
{
Array(3).fill(null).map((itemy,y) => (
this.renderSquare(3 * x + y)
))
}
</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 {
winnerName: squares[a],
winIndex: [a, b, c]
}
}
}
return null;
}
class Game extends React.Component {
constructor(props) {
super(props);
this.state = {
history: [{
squares: Array(9).fill(null)
}],
xIsNext: true,
stepNumber: 0,
sort: true
};
}
handleClick(i) {
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,
lastIndex: i
}]),
xIsNext: !this.state.xIsNext,
stepNumber: history.length
});
}
jumpTo(step) {
for (let i = 0; i < 9; i++) {
document.getElementsByClassName('square')[i].style = "";
}
this.setState({
stepNumber: step,
xIsNext: (step % 2) === 0
})
}
order() {
this.setState({
sort: !this.state.sort
})
}
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 + ' 最后落棋点(列号,行号):(' + parseInt(step.lastIndex / 3) + ', ' + step.lastIndex % 3 + ')':
'Go to game start';
return (
<li key={move}>
<button
onClick={() => this.jumpTo(move)}
className={move === this.state.stepNumber ? 'bold' : ''}>{desc}</button>
</li>
)
});
let status;
if (winner) {
status = 'Winner: ' + winner.winnerName;
for (let i of winner.winIndex) {
document.getElementsByClassName('square')[i].style = "background: lightblue; color: #fff;";
}
} else {
if (this.state.history.length > 9) {
status = 'No player win! It ends in a draw!';
} 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>
<button onClick={() => this.order()}>
{this.state.sort ? '倒序' : '正序'}
</button>
<ol>{this.state.sort ? moves : moves.reverse()}</ol>
</div>
</div>
);
}
}
ReactDOM.render(
<Game />,
document.getElementById('root')
);
index.css
body {
font: 14px "Century Gothic", Futura, sans-serif;
margin: 20px;
}
ol, ul {
padding-left: 30px;
}
.board-row:after {
clear: both;
content: "";
display: table;
}
.status {
margin-bottom: 10px;
}
.square {
background: #fff;
border: 1px solid #999;
float: left;
font-size: 24px;
font-weight: bold;
line-height: 34px;
height: 34px;
margin-right: -1px;
margin-top: -1px;
padding: 0;
text-align: center;
width: 34px;
}
.square:focus {
outline: none;
}
.kbd-navigation .square:focus {
background: #ddd;
}
.game {
display: flex;
flex-direction: row;
}
.game-info {
margin-left: 20px;
}
button.bold {
font-weight: bold;
}