http://www.freecodecamp.com/patrickcurl 's solution for Bonfire: Diff Two Arrays

bonfire-diff-two-arrays.js

// Bonfire: Diff Two Arrays
// Author: @patrickcurl
// Challenge: http://www.freecodecamp.com/challenges/bonfire-diff-two-arrays
// Learn to Code at Free Code Camp (www.freecodecamp.com)

function diff(arr1, arr2) {
  var newArr = [];
  arr1.forEach(function(a){
      if(arr2.indexOf(a) == -1){
        newArr.push(a);
      }
    });
  arr2.forEach(function(a){
      if(arr1.indexOf(a) == -1){
        newArr.push(a);
      }
    });
 
  return newArr.sort();
}

diff([1, 2, 3, 5], [1, 2, 3, 4, 5]);