Quick Sort O(n log n) in TypeScript

The best case is O(n log n), the worst is O(n^2)

function quickSort(arr: number[], lo: number, hi: number): void {
  if (lo >= hi) {
    return
  }

  const pivotInd = partition(arr, lo, hi)

  quickSort(arr, lo, pivotInd - 1)
  quickSort(arr, pivotInd + 1, hi)
}

function partition(arr: number[], lo: number, hi: number): number {
  const pivot = arr[hi]

  let ind = lo - 1

  for (let i = lo; i < hi; ++i) {
    if (arr[i] <= pivot) {
      ind = ind + 1
      const tmp = arr[i]
      arr[i] = arr[ind]
      arr[ind] = tmp
    }
  }

  ind = ind + 1
  arr[hi] = arr[ind]
  arr[ind] = pivot

  return ind
} 

const arr = [11, 13, 5, 10, 1, 9, 6, 44, 25]
quickSort(arr, 0, arr.length - 1)
console.log(arr)