不同类型循环上的 Javascript答案

【问题标题】：Javascript on different types of Loops不同类型循环上的 Javascript
【发布时间】：2019-05-16 01:23:32
【问题描述】：

这是一个关于条件的问题。现在，我搜索并看到了另一种（正确）的方法。但我就是不明白为什么我的方法行不通。：

问题：编写一个名为“getLongestOfThreeWords”的函数。

给定 3 个单词，“getLongestOfThreeWords”返回三个单词中最长的一个。

注意事项：

如果有平局，它应该返回平局中的第一个单词。

我理解“正确”的方式，但我的答案显示为“未定义”，似乎无法弄清楚原因..

"My way"    

function getLongestOfThreeWords(word1, word2, word3) {
if(word1.length > word2.length  && word1.length > word3.length){
    return word1;
} else if(word2.length > word1.length && word2.length > word3.length){
    return word2;
} else if (word3.length > word1.length && word3.length > word2.length){
    return word3;
} 
}

对

"correct way"

function getLongestOfThreeWords(word1, word2, word3) {
  let wordsArr = [word1, word2, word3];
  let longestWord = '';

  for (var i = 0; i < wordsArr.length; i++) {
    if (wordsArr[i].length > longestWord.length) {
      longestWord = wordsArr[i];
    } 
  }
  return longestWord;
}
var output = getLongestOfThreeWords('these', 'three', 'words');
console.log(output); // --> 'these'

【问题讨论】：

标签： javascript arrays string ecmascript-6

【解决方案1】：

因为您没有针对极端情况进行调整 - 当有两个词的长度相同并且该长度大于另一个词时。（另请注意，您的方式非常低效，甚至需要对多一个字进行大量调整）试试这个：

if (...) {...}
else if (...) {...}
else if (...) {...}
else if (word1.length == word2.length && word1.length > word3.length) {
    return word1;
}
else if (word2.length == word3.length && word2.length > word1.length) {
    return word3;
}

【讨论】：

【解决方案2】：

function getLongestOfThreeWords(word1, word2, word3) {
    if(word1.length >= word2.length  && word1.length >= word3.length){
        return word1;
    } else if(word2.length >= word1.length && word2.length >= word3.length){
        return word2;
    } else if (word3.length >= word1.length && word3.length >= word2.length){
        return word3;
    } 
}

【讨论】：

【解决方案3】：

function getLongestOfThreeWords(word1, word2, word3) {
  
  var newArr = [word1, word2, word3];
  
  
  //variable for longest string and array for elements to 
  //be pushed to that meet conditions
  var longWord = newArr[0].length;
  var doubleArr = [];

  //iterate,
  for(var i = 0; i < newArr.length; i++) {
    //if element length is longer than longWord,
    if(newArr[i].length > longWord) {
      //replace longWord,
      longWord = newArr[i].length;
      doubleArr = [];
        //push element into doubleArr.
        doubleArr.push(newArr[i]);
    } else {
      //edge case if there is more than one word tied for longest.
      if(newArr[i].length === longWord){
        //places that word in the next index.
        doubleArr.push(newArr[i]);
      }
    }
  }
  //return the first element that met the longest condition.
  return doubleArr[0];
}
var output = getLongestOfThreeWords('these', 'three', 'words');
console.log(output); // --> 'these'

【讨论】：