javascript 未捕获的类型错误：无法读取未定义的属性“2”
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Uncaught TypeError: Cannot read property '2' of undefined
提问by b2norma
The following is code for a TicTacToe program. I'm trying to write OO. I'm getting a Uncaught TypeError: Cannot read property '2' of undefined in the checkIfPositionIsTaken function when I click a box on my grid.
以下是井字游戏程序的代码。我正在尝试编写 OO。当我单击网格上的一个框时，我收到 Uncaught TypeError: Cannot read property '2' of undefined in the checkIfPositionIsTaken 函数。
The following is the constructor for the TicTacToe Object:
以下是井字游戏对象的构造函数：
var TicTacToe = function () {
this.player1Name = "Player 1";
this.player2Name = "Player 2";
var turn = "";
var grid = [[0,0,0],[0,0,0],[0,0,0]];
var hasWinner = 0;
var moveCount = 0;
}
The following is the checkIfPositionIsTaken function. I believe the error is on this.grid but it is defined when the object is created.
下面是 checkIfPositionIsTaken 函数。我相信错误在 this.grid 上，但它是在创建对象时定义的。
// Check If Position Is Taken
TicTacToe.prototype.checkIfPositionIsTaken = function(row, col){
if(this.grid[row][col] !== 0){
alert("This position is taken. Please try other position.");
return true;
}
else{
return false;
}
};
The following is where I create the TicTacToe object:
下面是我创建井字游戏对象的地方：
var theGame = new TicTacToe();
The following is my event for clicking a box on my grid:
以下是我单击网格上的框的事件：
// Column click event
$(".col").click(function(){
var row = $(this).parent().index();
var col = $(this).index();
if(theGame.checkIfPositionIsTaken(row, col) == false && theGame.checkIfGameHasEnded() == false){
if(theGame.turn == theGame.player1Name){
$(this).text(theGame.drawO(row, col));
if(theGame.winnerCheck(1,theGame.player1Name) == false && theGame.checkIfGameIsADraw() == false){
theGame.turn = theGame.player2Name;
theGame.setBoardMsg(theGame.player2Name+"'s turn now!");
}
return;
}
else{
$(this).text(theGame.drawX(row, col));
if(theGame.winnerCheck(2,theGame.player2Name) == false && theGame.checkIfGameIsADraw() == false){
theGame.turn = theGame.player1Name;
theGame.setBoardMsg(theGame.player1Name+"'s turn now!");
}
return;
}
}
});
This is my first question so just let me know if you need more information. Thanks.
这是我的第一个问题，所以如果您需要更多信息，请告诉我。谢谢。
采纳答案by epascarello
var grid = [[0,0,0],[0,0,0],[0,0,0]];
gridis a "local" variable to the TicTacToemethod so this.gridis going to be undefined.
grid是该TicTacToe方法的“本地”变量，因此this.grid将是未定义的。
You are going to have the same problems with turn, hasWinner, moveCount.
您将遇到与turn, hasWinner,相同的问题moveCount。
