由 for 循环生成的二维 JavaScript 数组被最后一个循环结果覆盖

Question

我正在尝试制作仅在行 Linear Feedback Shift Register 上工作的伪随机序列生成器。 我用 JavaScript 做这件事，因为它是我知道的唯一语言，并且我使用 HTML 来创建 GUI。 用户应输入初始值并获得原理图和伪随机序列本身。 这是我的 JavaScript 代码：

var UserInput = document.getElementById('ulaz');
var Output = document.getElementById('izlaz');

//variable `data` is an array of objects which I used to store pictures of circuits
// and [taps][3] necessary for shift registers to give max possible length output
// before going into loop which is 2^n-1, where n (`bit` in my code) is number of 
//register blocks and number of digits in input value.

function pss (){
    var data = [
        {
            slika:"pic/2bit.png",
            tap:[0,1]
        },
        {
            slika:"pic/3bit.png",
            tap:[0,2]
        },
        {
            slika:"pic/4bit.png",
            tap:[0,3]
        },
        {
            slika:"pic/5bit.png",
            tap:[1,4]
        },
        {
            slika:"pic/6bit.png",
            tap:[0,5]
        },
        {
            slika:"pic/7bit.png",
            tap:[0,6]
        },
        {
            slika:"pic/8bit.png",
            tap:[1,2,3,7]
        },
        {
            slika:"pic/9bit.png",
            tap:[3,8]
        },
        {
            slika:"pic/10bit.png",
            tap:[2,9]
        },
        {
            slika:"pic/11bit.png",
            tap:[1,10]
        },
        {
            slika:"pic/12bit.png",
            tap:[0,3,5,11]
        },
        {
            slika:"pic/13bit.png",
            tap:[0,2,3,12]
        },
        {
            slika:"pic/14bit.png",
            tap:[0,2,4,13]
        },
        {
            slika:"pic/15bit.png",
            tap:[0,14]
        },
        {
            slika:"pic/16bit.png",
            tap:[1,2,4,15]
        },
        {
            slika:"pic/17bit.png",
            tap:[2,16]
        },
        {
            slika:"pic/18bit.png",
            tap:[6,17]
        },
        {
            slika:"pic/19bit.png",
            tap:[0,1,4,18]
        },
        {
            slika:"pic/20bit.png",
            tap:[2,19]
        },
        {
            slika:"pic/21bit.png",
            tap:[1,20]
        },
        {
            slika:"pic/22bit.png",
            tap:[0,21]
        },
        {
            slika:"pic/23bit.png",
            tap:[4,22]
        },
        {
            slika:"pic/24bit.png",
            tap:[0,2,3,23]
        },
        {
            slika:"pic/25bit.png",
            tap:[2,24]
        },
        {
            slika:"pic/26bit.png",
            tap:[0,1,5,25]
        },
        {
            slika:"pic/27bit.png",
            tap:[0,1,4,26]
        },
        {
            slika:"pic/28bit.png",
            tap:[2,27]
        },
        {
            slika:"pic/29bit.png",
            tap:[0,28]
        },
        {
            slika:"pic/30bit.png",
            tap:[0,3,5,29]
        },
        {
            slika:"pic/31bit.png",
            tap:[2,30]
        },
        {
            slika:"pic/32bit.png",
            tap:[1,5,6,31]
        }
    ];
    var first = UserInput.value.split("");
        for (k=0;k<first.length;k++) first[k] = +first[k]; 
               //first is just UserInput separated in one char strings than parsed to integers
    var bit = first.length - 2;
          // I subtracted 2 here so I can access objects from data
    var matrix = [first];
    var t = 0;
    var between;
    var z;

    for (i=1; i<Math.pow(2, bit+2)-1; i++){     //here is that 2^n-1. +2 is because i had -2 before. For loop is starting from 1 and ending with <2^n-1 because i already have first array of matrix
        for (j=0; j<data[bit].tap.length; j++){
            z = data[bit].tap[j];
            t = t ^ matrix[i-1][z];
        }      // this for makes "t" which is all taps XOR-ed. If user input was 101, tap would be [0,2] and t would be 1xor1=0
        between = matrix[i-1];
            console.log(between);
        between.unshift(t);
        between.pop();
        matrix[i] = between;
        t=0;    // here Im "shifting registers" or just placing t in front of last generated row and removing its last digit, thus generating new row 
    }   
console.log(matrix);
}

而here 是 HTML，因此您可以运行它。

变量data 是一个对象数组，我用来存储电路图片，taps 是移位寄存器在进入循环之前提供最大可能长度输出所必需的，即 2^n-1，其中 n (@ 987654327@ 在我的代码中）是寄存器块的数量和输入值的位数。

所以问题是：console.log(between); 记录最后生成的行是正确的，除了，ofc，没有最后一行，因为它显示最后生成的，但是 console.log(matrix) 应该记录完整的矩阵，显示所有行被最后覆盖一。 所以对于用户输入 101，矩阵应该是

101
010
001
100
110
111
011

只是

011
011
011 ...

如果console.log(between); 之前的部分一切正常，我无法弄清楚它有什么问题......

附：代码未完成，HTML 中不会显示解决方案，还需要有部分函数从矩阵的最后一列生成数组，这是伪随机序列。

Answer 1

我意识到 var between 指的是与 var matrix[i-1] 相同的数组，而不是一个新的独立数组。

between = matrix[i-1];

所以，如果你只想存储 matrix[i-1] 的值，而不是创建引用，你可以这样做：

between = JSON.parse(JSON.stringify(matrix[i-1]));

在 js 中，当您将数组复制到某个变量中时，默认情况下会创建该数组的引用。有很多方法可以避免这种情况，你可以找到很多例子here。

Answer 2

我不知道为什么，但我已经找到了解决方案（有空时会进行更多调查）。

for (i=1; i<Math.pow(2, bit+2)-1; i++){     //here is that 2^n-1. +2 is because i had -2 before. For loop is starting from 1 and ending with <2^n-1 because i already have first array of matrix
    for (j=0; j<data[bit].tap.length; j++){
        z = data[bit].tap[j];
        t = t ^ matrix[i-1][z];
    }      // this for makes "t" which is all taps XOR-ed. If user input was 101, tap would be [0,2] and t would be 1xor1=0
    between = matrix[i-1];
    console.log(between);
    between.unshift(t);
    between.pop();
    // MODIFICATION
    var between_string = between;
    matrix[i] = between_string.join(); // Turn it to a string
    matrix[i] = matrix[i].split(','); // Turn it back to array to keep it working on the for loop above.
   // END MODIFICATION

    t=0;    // here Im "shifting registers" or just placing t in front of last generated row and removing its last digit, thus generating new row 
}   

现在，当您在控制台中打印出来时，它会显示一个双向数组，虽然这很奇怪，但有时（在我的控制台上）它会显示 int 数字，有时会与字符串数字混合（尊重 between 的原始值） .

编辑：我尝试只使用“101”作为输入。

第二次编辑：好吧，我很惭愧，它返回[1，“0”，“0”]（示例）的原因是因为 split(',') for "1,0,0"（仅两个数字前面有昏迷）。哈哈。对不起。