在JavaScript中查找字符串中最长单词的三种方法(推荐)

function findLongestWord(str) {
 return str.length;
}
findLongestWord("The quick brown fox jumped over the lazy dog");

var strSplit = “The quick brown fox jumped over the lazy dog”.split(‘ ‘);

var strSplit = [“The”, “quick”, “brown”, “fox”, “jumped”, “over”, “the”, “lazy”, “dog”];

var strSplit = 
[“T”, “h”, “e”, “ “, “q”, “u”, “i”, “c”, “k”, “ “, “b”, “r”, “o”, “w”, “n”, “ “, “f”, “o”, “x”, “ “, “j”, “u”, “m”, “p”, “e”, “d”, “ “, “o”, “v”, “e”, “r”, “ “, “t”, “h”, “e”, “ “, “l”, “a”, “z”, “y”, “ “, “d”, “o”, “g”];

function findLongestWord(str) {
 // Step 1. Split the string into an array of strings
 var strSplit = str.split(' ');
 // var strSplit = "The quick brown fox jumped over the lazy dog".split(' ');
 // var strSplit = ["The", "quick", "brown", "fox", "jumped", "over", "the", "lazy", "dog"];
 
 // Step 2. Initiate a variable that will hold the length of the longest word
 var longestWord = 0;

 // Step 3. Create the FOR loop
 for(var i = 0; i < strSplit.length; i++){
 if(strSplit[i].length > longestWord){ // If strSplit[i].length is greater than the word it is compared with...
 longestWord = strSplit[i].length; // ...then longestWord takes this new value
  }
 }
 /* Here strSplit.length = 9
  For each iteration: i = "The".length > 0)"quick".length > 3)"brown".length > 5)"fox".length > 5)"jumped".length > 5)"over".length > 6)"the".length > 6)"lazy".length > 6)"dog".length > 6)"The quick brown fox jumped over the lazy dog");

function findLongestWord(str) {
 var strSplit = str.split(' ');
 var longestWord = 0;
 for(var i = 0; i < strSplit.length; i++){
 if(strSplit[i].length > longestWord){
 longestWord = strSplit[i].length;
  }
 }
 return longestWord;
}
findLongestWord("The quick brown fox jumped over the lazy dog");

var sortArray = [“The”, “quick”, “brown”, “fox”, “jumped”, “over”, “the”, “lazy”, “dog”].sort();

var sortArray = [“The”, “brown”, “dog”, “fox”, “jumped”, “lazy”, “over”, “quick”, “the”];

[].sort(function(firstElement, secondElement) {  return secondElement.length — firstElement.length; })

function findLongestWord(str) {
 // Step 1. Split the string into an array of strings
 var strSplit = str.split(' ');
 // var strSplit = "The quick brown fox jumped over the lazy dog".split(' ');
 // var strSplit = ["The", "quick", "brown", "fox", "jumped", "over", "the", "lazy", "dog"];
 
 // Step 2. Sort the elements in the array
 var longestWord = strSplit.sort(function(a, b) { 
 return b.length - a.length;
 });
 /* Sorting process
 a   b   b.length  a.length  var longestWord
 "The"  "quick"   5   3   ["quick", "The"]
 "quick" "brown"   5   5   ["quick", "brown", "The"] 
 "brown" "fox"    3   5   ["quick", "brown", "The", "fox"]
 "fox"  "jumped"   6   3   ["jumped", quick", "brown", "The", "fox"]
 "jumped" "over"    4   6   ["jumped", quick", "brown", "over", "The", "fox"]
 "over"  "the"    3   4   ["jumped", quick", "brown", "over", "The", "fox", "the"]
 "the"  "lazy"    4   3   ["jumped", quick", "brown", "over", "lazy", "The", "fox", "the"]
 "lazy"  "dog"    3   4   ["jumped", quick", "brown", "over", "lazy", "The", "fox", "the", "dog"]
 */
 
 // Step 3. Return the length of the first element of the array
 return longestWord[0].length; // var longestWord = ["jumped", "quick", "brown", "over", "lazy", "The", "fox", "the", "dog"];
        // longestWord[0]="jumped" => jumped".length => 6
}

findLongestWord("The quick brown fox jumped over the lazy dog");

function findLongestWord(str) {
 var longestWord = str.split(' ').sort(function(a, b) { return b.length - a.length; });
 return longestWord[0].length;
}
findLongestWord("The quick brown fox jumped over the lazy dog");

[].reduce(function(previousValue, currentValue) {...}, “”);

function findLongestWord(str) {
 // Step 1. Split the string into an array of strings
 var strSplit = str.split(' ');
 // var strSplit = "The quick brown fox jumped over the lazy dog".split(' ');
 // var strSplit = ["The", "quick", "brown", "fox", "jumped", "over", "the", "lazy", "dog"];

 // Step 2. Use the reduce method
 var longestWord = strSplit.reduce(function(longest, currentWord) {
 if(currentWord.length > longest.length)
  return currentWord;
 else
  return longest;
 }, "");
 
 /* Reduce process
 currentWord  longest  currentWord.length  longest.length if(currentWord.length > longest.length)"The"    ""     3      0        yes       "The"
 "quick"   "The"    5      3        yes       "quick"
 "brown"   "quick"    5      5        no       "quick"
 "fox"    "quick"    3      5        no       "quick"
 "jumped"   "quick"    6      5        yes       "jumped"
 "over"   "jumped"   4      6        no       "jumped"
 "the"    "jumped"   3      6        no       "jumped"
 "lazy"   "jumped"   4      6        no       "jumped"
 "dog"    "jumped"   3      6        no       "jumped"
 */
 
 // Step 3. Return the length of the longestWord
 return longestWord.length; // var longestWord = "jumped" 
        // longestWord.length => "jumped".length => 6
}

findLongestWord("The quick brown fox jumped over the lazy dog");

function findLongestWord(str) {
 var longestWord = str.split(' ').reduce(function(longest, currentWord) {
 return currentWord.length > longest.length "");
 return longestWord.length;
}
findLongestWord("The quick brown fox jumped over the lazy dog");