javascript - 我访问的 JavaScript 对象是否错误(或者为什么这不起作用)？

Question

对于我用 JavaScript 创建的第一个(正确的)游戏，我正在制作贪吃蛇游戏。我将所有关于蛇的信息存储在这样的类中:

var snake={

    //The width and height of each "segment" of the snake (in pixels)
    size : 20,


    /*Direction that the snake's moving in

    Left=0
    Right=1
    Up=2
    Down=3*/
    direction : rand_int_between(0,3),


    /*Positions of the snake's "segments" (1 is the snake's head, then 2 (when it's created) will be the next segment of the snake,
    then 3 will be the next, and so on*/
    positions : {
        1 : {
            "x" : rand_int_between(0, 35)*snake.size, //There are 36 possible "columns" that the snake can be in
            "y" : rand_int_between(0, 23)*snake.size
        }
    },


    //Will be set to False if the game hasn't started or of it's paused
    moving : false
}

//Alert(snake.size);

现在这出于某种原因破坏了我的代码。当我将随机整数乘以“snake.size”时，我已将其精确定位，因为如果我将这些行更改为简单地将其乘以 20，则脚本可以正常工作。

我感觉这是其中一个问题，一旦您听到它，您将无法相信自己错过了它!

有人可以帮忙吗，因为这让我发疯了，哈哈。我认为我没有错误地访问“size”属性，因为如果我取消注释该代码的最后一行，然后从 positions 属性中删除“snake.size”位，它会像您一样提醒“20”期待。

这里是 rand_int_between():

function rand_int_between(min, max) { //Will include min and max
    return Math.floor(Math.random() * (max - min + 1)) + min;
}

Answer 1

您不能在声明对象时访问对象的元素 (snake)。尝试移动位置声明:

var snake={

    //The width and height of each "segment" of the snake (in pixels)
    size : 20,


    /*Direction that the snake's moving in

    Left=0
    Right=1
    Up=2
    Down=3*/
    direction : rand_int_between(0,3),


    //Will be set to False if the game hasn't started or of it's paused
    moving : false
};


/*Positions of the snake's "segments" (1 is the snake's head, then 2 (when it's created) will be the next segment of the snake,
    then 3 will be the next, and so on*/
snake.Positions = {
    1 : {
        "x" : rand_int_between(0, 35)*snake.size, //There are 36 possible "columns" that the snake can be in
        "y" : rand_int_between(0, 23)*snake.size
    }
};