在JavaScript类方法中,无法使用';这';在addEventListener()内部,甚至使用箭头函数。如何解决这个问题
我为井字游戏写了一节课。代码运行良好,但我必须在类定义中使用对象名来调用一些方法,而不是“this”关键字。当方法作为回调传递给addEventListener()时,就会出现问题。 我试图通过使用箭头函数定义方法来解决这个问题。但JS显示错误“无法读取未定义属性”错误。 我将如何克服这种情况 下面是类的实现。你可以看到我用game.turnClick代替了这个.turnClick在JavaScript类方法中,无法使用';这';在addEventListener()内部,甚至使用箭头函数。如何解决这个问题,javascript,class,methods,this,arrow-functions,Javascript,Class,Methods,This,Arrow Functions,我为井字游戏写了一节课。代码运行良好,但我必须在类定义中使用对象名来调用一些方法,而不是“this”关键字。当方法作为回调传递给addEventListener()时,就会出现问题。 我试图通过使用箭头函数定义方法来解决这个问题。但JS显示错误“无法读取未定义属性”错误。 我将如何克服这种情况 下面是类的实现。你可以看到我用game.turnClick代替了这个.turnClick class TicTacToe{ constructor(aiPlayer,humanPlayer
class TicTacToe{
constructor(aiPlayer,humanPlayer){
this.aiPlayer=aiPlayer;
this.humanPlayer=humanPlayer;
this.winCombos=[
[0,1,2],
[3,4,5],
[6,7,8],
[0,3,6],
[1,4,7],
[2,5,8],
[0,4,8],
[2,4,6]
];
this.originalBoard=Array.from(Array(9).keys());
this.gameWon=null;
this.cells=document.querySelectorAll('.cell');
}
startGame(){
//const cells=document.querySelectorAll('.cell');
this.cells.forEach(function(cell){
cell.innerHTML="";
cell.addEventListener('click',game.turnClick);
})
}
turnClick(e){
game.turn(e.target.id,game.humanPlayer);
if(!game.isTie()&&!game.gameWon){
window.setTimeout(function(){
game.turn(game.bestSquare(),game.aiPlayer);
game.isTie();
},1500);
}
}
turn(squareId,player){
this.originalBoard[squareId]=player;
const square=document.getElementById(squareId);
square.innerHTML=player;
document.querySelector('#click').play();
square.removeEventListener('click',game.turnClick);
this.gameWon=this.checkWin(this.originalBoard,player);
if(this.gameWon){
this.gameOver();
}
}
checkWin(board,player){
let playedSquares=[];
board.forEach(function(el,i){
if(el===player){
playedSquares.push(i);
}
})
console.log(playedSquares);
for(let [index,win] of this.winCombos.entries()){
if(win.every((el)=>{return playedSquares.includes(el)})){
return {index,player};
break;
}
}
return null;
}
gameOver(){
for(let index of this.winCombos[this.gameWon.index] ){
const square=document.getElementById(index);
square.style.backgroundColor= this.gameWon.player===this.humanPlayer?"blue":"red";
}
//const cells=document.querySelectorAll('button.cell');
this.cells.forEach(function(cell){
cell.removeEventListener('click',game.turnClick);
});
this.declareWin(this.gameWon.player===this.humanPlayer?'You Won !!! Hurray...':'You loose,AI beat you...');
}
emptySquares(){
return this.originalBoard.filter((el)=>typeof el==='number');
}
bestSquare(){
//return this.emptySquares()[0];
return this.minimax(this.originalBoard, this.aiPlayer).index;
}
isTie(){
if(this.emptySquares().length===0&& !this.gameWon){
this.cells.forEach(function(cell){
cell.style.backgroundColor='green';
cell.removeEventListener('click',game.turnClick);
});
this.declareWin(' You managed tie the game. congrats !!!');
return true;
}
else{
return false;
}
}
declareWin(msg){
if(msg.includes('won')||msg.includes('tie')){
document.querySelector('#winOrTie').play();
}
else{
document.querySelector('#lost').play();
}
document.querySelector('.endgame .message').innerText=msg;
document.querySelector('.endgame').classList.add('show');
}
minimax(newBoard,player){
let availSpots = this.emptySquares();
if (this.checkWin(newBoard, this.humanPlayer)) {
return {score: -10};
} else if (this.checkWin(newBoard, this.aiPlayer)) {
return {score: 10};
} else if (availSpots.length === 0) {
return {score: 0};
}
let moves = [];
for (let i = 0; i < availSpots.length; i++) {
let move = {};
move.index = newBoard[availSpots[i]];
newBoard[availSpots[i]] = player;
if (player === this.aiPlayer) {
let result = this.minimax(newBoard, this.humanPlayer);
move.score = result.score;
} else {
let result = this.minimax(newBoard, this.aiPlayer);
move.score = result.score;
}
newBoard[availSpots[i]] = move.index;
moves.push(move);
}
let bestMove;
if(player === this.aiPlayer) {
let bestScore = -10000;
for(let i = 0; i < moves.length; i++) {
if (moves[i].score > bestScore) {
bestScore = moves[i].score;
bestMove = i;
}
}
} else {
let bestScore = 10000;
for(let i = 0; i < moves.length; i++) {
if (moves[i].score < bestScore) {
bestScore = moves[i].score;
bestMove = i;
}
}
}
return moves[bestMove];
}
}
classtictactoe{
构造函数(aiPlayer、humanPlayer){
this.aiPlayer=aiPlayer;
this.humanPlayer=humanPlayer;
这是winCombos=[
[0,1,2],
[3,4,5],
[6,7,8],
[0,3,6],
[1,4,7],
[2,5,8],
[0,4,8],
[2,4,6]
];
this.originalBoard=Array.from(Array(9.keys());
this.gameWon=null;
this.cells=document.querySelectorAll('.cell');
}
startGame(){
//const cells=document.queryselectoral('.cell');
this.cells.forEach(函数(单元格){
cell.innerHTML=“”;
cell.addEventListener('click',game.turnClick);
})
}
点击按钮(e){
游戏。回合(例如,target.id,game.humanPlayer);
如果(!game.isTie()&&!game.gameWon){
setTimeout(函数(){
game.turn(game.bestSquare(),game.aiPlayer);
game.isTie();
},1500);
}
}
转身(方线,球员){
这个.originalBoard[squared]=玩家;
const square=document.getElementById(squareId);
square.innerHTML=player;
document.querySelector('#click').play();
square.removeEventListener('click',game.turnClick);
this.gameWon=this.checkWin(this.originalBoard,player);
如果(this.gameWon){
这是gameOver();
}
}
checkWin(棋盘、玩家){
让playedSquares=[];
董事会主席(职能(el,i){
如果(el==玩家){
游戏方块。推(i);
}
})
控制台.log(playedSquares);
对于(让[index,win]this.winCombos.entries()){
if(win.every((el)=>{return playedSquares.includes(el)})){
返回{index,player};
打破
}
}
返回null;
}
gameOver(){
for(让我们索引this.winCombos[this.gameWon.index]){
const square=document.getElementById(索引);
square.style.backgroundColor=this.gameWon.player==this.humanPlayer?“蓝色”:“红色”;
}
//const cells=document.querySelectorAll('button.cell');
this.cells.forEach(函数(单元格){
cell.removeEventListener('click',game.turnClick);
});
这个.declareWin(这个.gameWon.player==这个.humanPlayer?“你赢了!!!万岁…”:“你输了,AI赢了你…”);
}
空方块(){
返回这个.originalBoard.filter((el)=>typeof el==='number');
}
bestSquare(){
//返回此.emptySquares()[0];
返回this.minimax(this.originalBoard,this.aiPlayer).index;
}
isTie(){
if(this.emptySquares().length==0&&!this.gameWon){
this.cells.forEach(函数(单元格){
cell.style.backgroundColor='green';
cell.removeEventListener('click',game.turnClick);
});
这个。declareWin(‘你打平了比赛。恭喜!!!’);
返回true;
}
否则{
返回false;
}
}
declareWin(味精){
if(msg.includes('won')| | msg.includes('tie')){
document.querySelector('#winOrTie').play();
}
否则{
document.querySelector('\35; lost').play();
}
document.querySelector('.endgame.message')。innerText=msg;
document.querySelector('.endgame').classList.add('show');
}
极小极大值(新手,玩家){
设availSpots=this.emptySquares();
if(这个.checkWin(newBoard,这个.humanPlayer)){
返回{分数:-10};
}否则如果(这个.checkWin(新板,这个.aiPlayer)){
返回{分数:10};
}else if(availSpots.length==0){
返回{score:0};
}
让我们移动=[];
for(设i=0;i最佳分数){
最佳得分=移动[i]。得分;
bestMove=i;
}
}
}否则{
让bestScore=10000;
for(设i=0;i
下面是包含完整代码的gitHub存储库
您可能需要将回调方法的上下文绑定到实例。是否
game
是全局变量?为什么要在一个特定实例上调用方法而不是使用this
?“this”不起作用。这就是为什么我必须创建一个类的全局变量
cell.addEventListener('click',game.turnClick.bind(game));