我有以下代碼來顯示帶有用于自動(dòng)完成的單詞的列表：var words = ['foo', 'bar', 'barz', 'ba'];var possibleWords = [];  document.getElementsByTagName('div')[0].addEventListener('keyup', function(){        var textWords = this.innerText.split(' ');  var lastWord = textWords[textWords.length-1];  for(var k = 0; k < words.length; k++){          for(n = 0; n < 20; n++){                if(lastWord.length == n+1 && words[k].charAt(n) == lastWord.charAt(n)){        possibleWords.push(words[k]);                    var counts = possibleWords.reduce((a, c) => {          a[c] = (a[c] || 0) + 1;          return a;        }, {});        var maxCount = Math.max(...Object.values(counts));        var mostFrequent = Object.keys(counts).filter(k => counts[k] === maxCount);      }    }  }        console.log(mostFrequent);        var list = this.getElementsByTagName('ul')[0];  if(mostFrequent == undefined) {    list.removeAttribute('style');  } else {          list.style.display = 'inline';    list.innerHTML = '';    list.innerHTML = '<li>'+mostFrequent.join('</li><li>')+'</li>';  }});div{width:300px;height:100px;outline:1px solid #ccc;position:relative;}ul{display:none;position:absolute;left:0;top:100px;}<div contenteditable="true"><ul></ul></div>當(dāng)我從var list = ...to注釋底部代碼list.innerHTML = '<li>'+...并嘗試鍵入b，然后是ba，然后是bar，然后是barz 時(shí)，我在控制臺(tái)中看到了正確的結(jié)果。但是如果我不注釋底部代碼，我會(huì)收到undefined一半的時(shí)間并且列表也有一半的時(shí)間是隱藏的。如何解決問題？