Longest Palindrome

LongestPalindrome.js

//create freq obj for each letter, iterate over 
  //if even, increment a counter of its value 
  //if odd > 1, increment counter value - 1 
  //if odd = 1, dont count it. 
  //at end you can add 1 to account for letters that have freq of one. (create variable for this)
    //can only happen once (assuming letter w/ freq of 1 exists.)
  //ex's. '' - 0, abc - 1, abbc - 3, aaabb - 5, zzz - 3, aaabbcde- 5

var longestPalindrome = function(s) {
    var freq = {}, longest = 0, hasOdd = false;
    s = s.split("");
    s.forEach(function(letter){
       freq[letter] = freq[letter] + 1 || 1; 
    });
    
    for (var key in freq) {
      if(freq[key] % 2 === 0) {
        longest += freq[key];
      } else {
        hasOdd = true; 
        longest += freq[key] - 1;          
      }
    }

    return hasOdd ? longest + 1 : longest; //if no letters of freq 1, aabbbaa works. if has it, then adds it back once. 
};