Return the first word with the greatest number of repeated letters

Question

This is a question from coderbyte’s easy set. Many people asked about it already, but I’m really curious about what’s wrong with my particular solution (I know it’s a pretty

Answer 1

Yet another solution in a more functional programming style:

JavaScript

function LetterCountI(str) {
  return ((str = str.split(' ').map(function(word) {
    var letters = word.split('').reduce(function(map, letter) {
          map[letter] = map.hasOwnProperty(letter) ? map[letter] + 1 : 1;
          return map;
        }, {}); // map of letters to number of occurrences in the word

    return {
      word: word,
      count: Object.keys(letters).filter(function(letter) {
        return letters[letter] > 1;
      }).length // number of repeated letters
    };
  }).sort(function(a, b) { // Sort words by number of repeated letters
    return b.count - a.count;
  }).shift()) && str.count && str.word) || -1; // return first word with maximum repeated letters or -1
}

console.log(LetterCountI('Today, is the greatest day ever!')); // => greatest

Plunker

http://plnkr.co/edit/BRywasUkQ3KYdhRpBfU2?p=preview