merge sort in javascript

mergesort.js

function merge(arr, l, m, r) {
  let i, j, k;
  let n1 = m - l + 1;
  let n2 = r - m;
  /* create temp arrays */
  let L = new Array(n1);
  let R = new Array(n2);
  /* Copy data to temp arrays L[] and R[] */
  for (i = 0; i < n1; i++)
    L[i] = arr[l + i];
  for (j = 0; j < n2; j++)
    R[j] = arr[m + 1 + j];
  /* Merge the temp arrays back into arr[l..r]*/
  i = 0; // Initial index of first subarray 
  j = 0; // Initial index of second subarray 
  k = l; // Initial index of merged subarray 
  while (i < n1 && j < n2) {
    if (L[i] <= R[j]) {
      arr[k] = L[i];
      i++;
    }
    else {
      arr[k] = R[j];
      j++;
    }
    k++;
  }
  /* Copy the remaining elements of L[], if there are any */
  while (i < n1) {
    arr[k] = L[i];
    i++;
    k++;
  }
  /* Copy the remaining elements of R[], if there are any */
  while (j < n2) {
    arr[k] = R[j];
    j++;
    k++;
  }
}

/* l is for left index and r is right index of the sub-array of arr to be sorted */
function mergeSort(arr, l, r) {
  console.log(arr);
  if (l < r) {
    // Same as (l+r)/2, but avoids overflow for large l and h 
    let m = Math.floor(l + (r - l) / 2);
    // Sort first and second halves 
    mergeSort(arr, l, m);
    mergeSort(arr, m + 1, r);
    merge(arr, l, m, r);
  }
}

const unsorted = [8, 7, 6, 5, 4, 3, 2, 1, -4, -1000, 327, 14011904, 115011017];
console.log(unsorted.length);

mergeSort(unsorted, 0, unsorted.length - 1);

console.log(unsorted);