Javascript reduce() to find the shortest word in a string

问题

I have a function that finds the longest word in a string.

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

I'm having a hard time converting this to find the shortest word. Why can't I just change currentWord.length > longestWord.length to currentWord.length < longestWord.length?

回答1:

You need to provide an initial value to the reduce function, otherwise a blank string is the shortest word:

function findShortestWord(str) {
  var words = str.split(' ');
  var shortest = words.reduce((shortestWord, currentWord) => {
    return currentWord.length < shortestWord.length ? currentWord : shortestWord;
  }, words[0]);
  return shortest;
}
console.log(findShortestWord("The quick brown fox jumped over the lazy dog"));

回答2:

While using reduce, initialValue is optional and if it isn't provided then your first element will be used as initialValue. So, in your case, you'll just have to remove your "":

function findLongestWord(str) {
  var longest = (typeof str == 'string'? str : '')
    .split(' ').reduce((longestWord, currentWord) =>{
      return currentWord.length < longestWord.length ? currentWord : longestWord;
  });
  return longest;
}
console.log(findLongestWord("The quick brown fox jumped over the lazy dog")); // The

回答3:

I coded it in this way

const findLongestWord = str => {
  return typeof str === 'string' 
  ? str.split(' ').reduce((sw, lw) => lw.length < sw.length ? lw :sw)
  : '';
}
console.log(findLongestWord('The quick brown fox jumps over the lazy dog.')); //'The'

来源：https://stackoverflow.com/questions/49124172/javascript-reduce-to-find-the-shortest-word-in-a-string

标签

javascript

arrays

ecmascript-6

reduce