Javascript下一个、上一个、来自数组的随机

我已经创建了一个数组，当你点击random word按钮时会选择一个随机单词，但是我一直在创建next和previous，以便逐步浏览列表

<Script>
        window.onload = myFunction;

        var WordList = ["a", "b", "c", "d"];
        var Word

        function myFunction() {
        var Word = WordList[Math.floor(Math.random()*WordList.length)];
        document.getElementById("Word").innerHTML = Word;
        }

        function NextWord() {
        var a = WordList.indexOf("Word");

        document.getElementById("Word").innerHTML = a;

    </script>

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nextWord函数没有右括号，您正在查找字符串单词的索引，您更希望查找变量单词的索引，如下所示

    function NextWord() {
      var a = WordList.indexOf(Word) ;

      /// check if last entry 
      if((a + 1) == WordList.length) {
         /// reset
         a = 0;
      }else {
         /// increment
         a += 1;
      }
      /// set innerhtml
      document.getElementById("Word").innerHTML = WordList[a];
    }

---

您可以对上一个Word执行相同的操作，缓存数组的当前索引

var currentIndex = 0, wordList = ["a", "b", "c", "d"];

function randomWord() {
  currentIndex = Math.floor(Math.random() * wordList.length);
  return wordList[currentIndex];
}

function nextWord() {
  currentIndex += 1;
  currentIndex = Math.min(currentIndex, wordList.length - 1);
  return wordList[currentIndex];
}

function prevWord() {
  currentIndex -= 1;
  currentIndex = Math.max(currentIndex, 0);
  return wordList[currentIndex];
}

---

这是打字错误吗？你从未关闭过你的NextWord函数。WordList.indexOfWord；返回-1，因为Word不在该数组中。我认为它应该是Math.mincurrentIndex，wordList.length-1Wow。。非常感谢。我用了这个，它工作了，除了下一个，当它结束时，得到了一个未定义的。我认为它已经超过了arraymy的错误，请检查a+1==Wordlist.length