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
;
}
最终效果：
