quick-sort.js

function quickSort(array, low, high) {
  if (low < high) {
    const p = partition(array, low, high);
    quickSort(array, low, p);
    quickSort(array, p + 1, high);
  }
}

function partition(array, low, high) {
  const middleIndex = Math.floor((high + low) / 2);
  const pivot = array[middleIndex];
  let i = low;
  let j = high;

  while (true) {
    while (array[i] < pivot) {
      i += 1;
    }
    while (array[j] > pivot) {
      j -= 1;
    }
    if (j <= i) {
      return j;
    }
    // we found a i for which array[i] is greater than the pivot
    // and a j for which array[j] is smaller than the pivot so we swap them
    const temp = array[i];
    array[i] = array[j];
    array[j] = temp;
  }
}