self.swap = function(arr, i, j) {
   var temp = arr[i];
   arr[i] = arr[j];
   arr[j] = temp;
}

self.partition = function (arr, pivot, left, right){
   var pivotValue = arr[pivot],
       partitionIndex = left;

   for(var i = left; i < right; i++){
    if(arr[i] < pivotValue){
      swap(arr, i, partitionIndex);
      partitionIndex++;
    }
  }
  swap(arr, right, partitionIndex);
  return partitionIndex;
}

self.quickSort = (arr, left, right) => {
   var len = arr.length,
   pivot,
   partitionIndex;

  if(left < right){
    pivot = right;
    partitionIndex = partition(arr, pivot, left, right);

   //sort left and right
   quickSort(arr, left, partitionIndex - 1);
   quickSort(arr, partitionIndex + 1, right);
  }
  return arr;
}