javascript - 当我删除重复项时，为什么会得到 NaN 值以及魔方打乱生成器的末尾？

Question

我正在为 Fitbit 开发一个魔方应用程序，反之亦然，我遇到了从数组中删除重复项的问题，因为一旦从列表末尾删除了重复项，在组合数组时我会收到 NaN 错误，而且这种情况只会发生当我在数组末尾进行拼接时，我无法弄清楚这不起作用的原因

function getScramble(number_of_moves, faces, modifiers, scramble_faces, scramble_modifiers, scramble) {

  for (var i = 0; i < number_of_moves; i++) {
    var sample = faces[Math.floor(Math.random() * faces.length)];
    var mod = modifiers[Math.floor(Math.random() * modifiers.length)];
    scramble_faces[i] = sample;
    scramble_modifiers[i] = mod;
    if (scramble_faces[i] == scramble_faces[i - 1]) {
      scramble_faces[i] = faces[Math.floor(Math.random() * faces.length)];
    }
  }
  removeDuplicates(scramble_faces, scramble_modifiers)
  for (var i = 0; i < number_of_moves - 2; i++) {
    scramble[i] = scramble_faces[i] + scramble_modifiers[i]
  }

  console.log(scramble);

  let demotext = document.getElementById("demotext");
  demotext.text = scramble;
  scramble = [];
  scramble_faces = [];
  scramble_modifiers = [];
}

function threebythree() {
  var faces = ["U", "D", "L", "R", "F", "B"];
  var modifiers = ["", "'", "2"];
  var scramble_faces = [];
  var scramble_modifiers = [];
  var scramble = [];
  var number_of_moves = 22;
  let Title1 = document.getElementById("title");
  Title1.text = "3x3"
  getScramble(number_of_moves, faces, modifiers, scramble_faces, scramble_modifiers, scramble, Title1)
}

function removeDuplicates(arr, arr2, number_of_moves) {
  var t = 0;
  var new_arr = arr;
  var new_arr2 = arr2;
  for (var i = new_arr.length - 1; i >= 0; i--) {
    if (new_arr[i] === new_arr[i - 1]) {
      new_arr.splice(i, 1);
      new_arr2.splice(i, 1);
    }
  }
  arr = new_arr;
  arr2 = new_arr2;
  new_arr = [];
  new_arr2 = [];
  new_arr.pop();
  new_arr2.pop();

  console.log(arr);
  console.log(arr2);
}

Answer 1

scramble_faces 和 scramble_modifiers 的长度最初为 number_of_moves。但是当你删除它们中的重复项后，它可能会更短。但您仍然在下一个 for 循环的限制中使用 number_of_moves 。因此，当您尝试添加不再存在的元素时，您会得到未定义。 未定义+未定义== NaN。

您应该使用其中一个数组的长度:

function getScramble(number_of_moves, faces, modifiers, scramble_faces, scramble_modifiers, scramble) {

  for (var i = 0; i < number_of_moves; i++) {
    var sample = faces[Math.floor(Math.random() * faces.length)];
    var mod = modifiers[Math.floor(Math.random() * modifiers.length)];
    scramble_faces[i] = sample;
    scramble_modifiers[i] = mod;
    if (scramble_faces[i] == scramble_faces[i - 1]) {
      scramble_faces[i] = faces[Math.floor(Math.random() * faces.length)];
    }
  }
  removeDuplicates(scramble_faces, scramble_modifiers)
  for (var i = 0; i < scramble_faces.length - 2; i++) {
    scramble[i] = scramble_faces[i] + scramble_modifiers[i]
  }

  console.log(scramble);

  let demotext = document.getElementById("demotext");
  demotext.text = scramble;
  scramble = [];
  scramble_faces = [];
  scramble_modifiers = [];
}