My solution for FreeCodeCamp | Pig Latin exercise.

FreeCodeCamp | Pig Latin.js

function translatePigLatin(str) {
 var prefix = '';
 str.split('').some(function(char) {
   if (char.isVowel())
     return true;
   else
     prefix += char;
 });  
 return str.substr(prefix.length, str.length) + (prefix || 'w') + 'ay';
}

function isVowel() {
  var self = this;
  var vowels = ['a', 'e', 'i', 'o', 'u'];
  return vowels.some(function(vowel) {
    return self == vowel;
  });
}

Object.prototype.isVowel = isVowel;