在 Javascript 中选择随机数组元素时出错：无法读取未定义的属性

Question

我想从数组中随机选取一个元素而不重复，但是发生了错误：Cannot read properties of undefined (reading 'sound')。

这是我的代码：

var words = [
  { word: 'major', sound: 'major.mp3'},
  { word: 'apply', sound: 'apply.mp3'},
  { word: 'blue',  sound: 'blue.mp3' },
  { word: 'cat',   sound: 'cat.mp3'  },
  { word: 'class', sound: 'class.mp3'},
  { word: 'code',  sound: 'code.mp3' },
  { word: 'cook',  sound: 'cook.mp3' },
  { word: 'daisy', sound: 'daisy.mp3'},
  { word: 'ease',  sound: 'ease.mp3' },
  { word: 'idea',  sound: 'idea.mp3' }
];

var randomWord = words[Math.floor(Math.random() * words.length - 5)]; // just added - 5 here
var audio = new Audio();
var playBtn = document.getElementById("play-button");
var guessBtn = document.getElementById("guess-button");
var nextBtn = document.getElementById("next-button");
var correct = document.getElementById("correct");
var incorrect = document.getElementById("incorrect");

playBtn.addEventListener("click", function() {
  audio.src = randomWord.sound;
  audio.play();
  var name = words.splice(randomWord,1); // just added
  words.push(name); // just added
  })

guessBtn.addEventListener("click", function() {
  var inputBox = document.getElementById("input-box").value;

  if (inputBox == randomWord.word) {
    correct.innerHTML = "Correct!"
  }
  else {
    incorrect.innerHTML = "Incorrect"
  }
})

nextBtn.addEventListener("click", function() {
  location.reload();
})

音频播放流畅，直到我试图让它不再重复。我做错了吗？

Answer 1

words[Math.floor(Math.random() * (words.length - 1))];

我觉得你需要这样使用。

因为 Math.floor(Math.random() * words.length - 5) 可以小于 0

Answer 2

您可以考虑：1) 构建从 0 到 words.length 的索引数组，2) 选择随机索引 3) 使用随机索引获取单词（单词将是随机的）4) 删除随机索引避免重复。这样，您无需删除您的单词，您的随机索引将始终有效。

//----------New code-----------------
var indexes = []
for (let i=0; i<words.length; i++) {
    indexes.push(i)
}
//-----------------------------------




 playBtn.addEventListener("click", function() {
      //get a random index value
      let randomIndex = Math.floor((Math.random()*words.length))
       //Get your randomword here, using the random index
       var randomWord = words[randomIndex]; 
       //Delete the index so it will not repeat
       indexes.splice(randomIndex,1)
       //This is your code below
       audio.src = randomWord.sound;
       audio.play();
      //var name = words.splice(randomWord,1); // delete this!
      words.push(name); // just added >> is this required?
  })