Javascript独特的随机数生成器不生成唯一的数字

Question

我正在尝试一个新的随机数生成器，它应该生成没有重复的数字，但是当我尝试将其应用到我的页面时，它会产生许多重复项。至少 60% 的情况下会出现重复，一次重复三份，还有两组重复。

我正在尝试 Generate unique random numbers between 1 and 100 的答案，即使我将其限制为 20 个数字，它似乎也能正常工作。运行 40 次，重复数为零。当我试图将它放入现有的函数中时，它就崩溃了。知道我在这里缺少什么吗？这是我之前的问题Fill table with random images的延续

/* The part of what each image url has in common
   ⍟ var base = 'images/Image_'
   */
var base = 'images/Image_';
var suff = '.jpg';

function randomCellBG(base) {

  // Reference the <table>
  var T = document.getElementById('mainTable');

  /* Collect all .cell into a NodeList and convert
  || it into an array
  */
  var cellArray = Array.from(T.querySelectorAll('.cell'));

  // map() the array; run a function on each loop...
  cellArray.map(function(cel, idx) {

    // Get a random number 1 - 9
    var arr = []
    while (arr.length < 9) {
      var ran = Math.ceil(Math.random() * 40)
      if (arr.indexOf(ran) > -1) continue;
      arr[arr.length] = ran;
    }

    /* Concatenate base and random number to form
    || a string of a url of an image
    ⍟ result: "images/Image_08.jpg"
    */
    var img = base + ran.toString() + suff;

    /* Assign that url as the value to the 
    || backgroundImage property of the .cell
    || in current iteration
    */
    cel.innerHTML = "<img src='" + img + "'/>";

  });

}

Answer 1

如果我理解正确，那么您需要: 1. 将 map 更改为 forEach 2. 您需要将保存已生成数字的数组移出forEach函数3.更改数字生成器循环

/* The part of what each image url has in common
⍟ var base = 'images/Image_'
*/
var base = 'images/Image_';
var suff = '.jpg';

function randomCellBG(base) {

  // Reference the <table>
  var T = document.getElementById('mainTable');

  /* Collect all .cell into a NodeList and convert
  || it into an array
  */
  var cellArray = Array.from(T.querySelectorAll('.cell'));

  // initialize the array
  var arr = []
  // map() the array; run a function on each loop...
  cellArray.forEach(function (cel, idx) {

    // generate numbers 1-40 and check if they were already generated
    do {
      var ran = Math.ceil(Math.random() * 40)
    } while (arr.indexOf(ran) > -1);
    //save the newly generated unique number
    arr[arr.length] = ran;

    /* Concatenate base and random number to form
    || a string of a url of an image
    ⍟ result: "images/Image_08.jpg"
    */
    var img = base + ran.toString() + suff;

    /* Assign that url as the value to the 
    || backgroundImage property of the .cell
    || in current iteration
    */
    cel.innerHTML = "<img src='" + img + "'/>";
  });
}