javascript二维数组未返回正确的值

我正在测试一款石头纸剪刀蜥蜴斯波克游戏。我没有生成可能的结果，而是使用

var-matrix=[]

来捕获所有的可能性。在数组位置

矩阵[3,0]

，输入的字符串是“rock wins”。然而，我在数组之后运行了

console.log（矩阵[3,0]）

，它产生了一个不同的结果

有人能告诉我为什么吗

var matrix = [];

matrix[0,0] = "it's a tie";
matrix[0,1] = "Paper wins";
matrix[0,2] = "rock wins";
matrix[0,3] = "rock wins";
matrix[0,4] = "Spock wins";
matrix[1,0] = "Paper wins";
matrix[1,1] = "it's a tie";
matrix[1,2] = "Scissors win";
matrix[1,3] = "Lizard wins";
matrix[1,4] = "Paper wins";
matrix[2,0] = "rock wins";
matrix[2,1] = "Scissors win";
matrix[2,2] = "it's a tie";
matrix[2,3] = "Scissors win";
matrix[2,4] = "spock wins";
matrix[3,0] = "rock wins";

log.console(matrix[3,0]); //returns spock wins 

---

不，没有。它实际上返回“摇滚乐赢”。
简而言之，您使用了错误的语法

为什么会这样？ 如果您对理解JavaScript的神奇行为不感兴趣，您可能会错过这一部分，直接转到“应该是什么样子？”

您已经声明了一个一维数组

当您尝试分配或读取以下属性

矩阵[0,0]

时，

0,0

被识别为一个表达式，其计算结果为最后一个数字（在本例中为0）

意思是

matrix[0,0] = "it's a tie";
matrix[0,1] = "Paper wins";
matrix[0,2] = "rock wins";
// ...
matrix[2,3] = "Scissors win";
matrix[2,4] = "spock wins";
matrix[3,0] = "rock wins";
console.log(matrix[3,0]);

与

matrix[0] = "it's a tie";
matrix[1] = "Paper wins";
matrix[2] = "rock wins";
// ...
matrix[3] = "Scissors win";
matrix[4] = "spock wins";
matrix[0] = "rock wins";
console.log(matrix[0]); // returns "rock wins"

阅读更多关于它的信息

原因是您使用了错误的语法

应该怎样？ 这就是在JavaScript中访问多维数组中的值的方式：

var val = arr[key1][key2][key3]; // not arr[key1, key2, key3]

您的代码应该是这样的：

var矩阵=[]；
对于（var i=0；i<4；i++）矩阵[i]=[]；
矩阵[0][0]=“这是一个平局”；
矩阵[0][1]=“纸赢”；
矩阵[0][2]=“摇滚乐获胜”；
// ...
矩阵[2][3]=“剪刀赢”；
矩阵[2][4]=“斯波克获胜”；
矩阵[3][0]=“摇滚乐获胜”；
编写（矩阵[3][0]）；//代码中不包含矩阵[3,0]

：

matrix[0,0] = "it's a tie";

方括号中的部分是一个表达式，它被计算并强制为字符串。表达式

0,0

返回最后一个“，”之后的值，计算结果为

0

，

0,1

计算结果为1，依此类推

因此：

创建分配给每个索引的最后一个值的“一维”数组：

["rock wins", "Scissors win", "it's a tie", "Scissors win", "spock wins"]

及

评估为

matrix[0]

因此你会得到“摇滚乐赢”

你想要的是：

var matrix = [[],[],[],[]];

matrix[0][0] = "it's a tie";
matrix[0][1] = "Paper wins";
matrix[0][2] = "rock wins";
matrix[0][3] = "rock wins";
matrix[0][4] = "Spock wins";
matrix[1][0] = "Paper wins";
matrix[1][1] = "it's a tie";
matrix[1][2] = "Scissors win";
matrix[1][3] = "Lizard wins";
matrix[1][4] = "Paper wins";
matrix[2][0] = "rock wins";
matrix[2][1] = "Scissors win";
matrix[2][2] = "it's a tie";
matrix[2][3] = "Scissors win";
matrix[2][4] = "spock wins";
matrix[3][0] = "rock wins";

console.log(matrix[3][0]); // rock wins

您还可以使用数组文字：

var matrix = [
              ["it's a tie","Paper wins","rock wins","rock wins","Spock wins"],
              ["Paper wins","it's a tie","Scissors win","Lizard wins","Paper wins"],
              ["rock wins","Scissors win","it's a tie","Scissors win","spock wins"],
              ["rock wins"]
             ];

---

很难对我们看不到的代码进行评论…

matrix[3,0]

没有按照您的想法进行操作，请尝试

matrix[3][0]

。

var matrix = [[],[],[],[]];

matrix[0][0] = "it's a tie";
matrix[0][1] = "Paper wins";
matrix[0][2] = "rock wins";
matrix[0][3] = "rock wins";
matrix[0][4] = "Spock wins";
matrix[1][0] = "Paper wins";
matrix[1][1] = "it's a tie";
matrix[1][2] = "Scissors win";
matrix[1][3] = "Lizard wins";
matrix[1][4] = "Paper wins";
matrix[2][0] = "rock wins";
matrix[2][1] = "Scissors win";
matrix[2][2] = "it's a tie";
matrix[2][3] = "Scissors win";
matrix[2][4] = "spock wins";
matrix[3][0] = "rock wins";

console.log(matrix[3][0]); // rock wins

var matrix = [
              ["it's a tie","Paper wins","rock wins","rock wins","Spock wins"],
              ["Paper wins","it's a tie","Scissors win","Lizard wins","Paper wins"],
              ["rock wins","Scissors win","it's a tie","Scissors win","spock wins"],
              ["rock wins"]
             ];