Diff Two Arrays

diff_two_arrays.js

function diff(arr1, arr2) {
//just add two two arrays together
 var newArr = arr1.concat(arr2);
 //then filter it
 return newArr.filter(function(val){
 // return true if the value is not in one of the arrays
   if (arr1.indexOf(val) < 0 || arr2.indexOf(val) < 0){
     return true;
   }else{
     return false;
   }
 });
}


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