quick_sort-arrays-1.js

let array = [5, 5, 7, 2, 9, 1, 1, 1, -100, -2, 4, 3, 2, 8, 100, 9, 1];

function quickSort(array) {
  if (array.length <= 1) return array;

  let middleArray = [];
  let lessArray = [];
  let moreArray = [];

  let middleIndex = Math.floor(array.length / 2);
  let middleElem = array[middleIndex];

  for (let i = 0; i < array.length; i++) {
    if (array[i] > middleElem) {
      moreArray.push(array[i]);
    } else if (array[i] == middleElem) {
      middleArray.push(array[i]);
    } else {
      lessArray.push(array[i]);
    }
  }

  return [...quickSort(lessArray), ...middleArray, ...quickSort(moreArray)];
}

console.log(quickSort(array));