Three-Way Quick Sort for Duplicate Keys

export function quickSort(items, compare = defaultCompare) {
  if (!Array.isArray(items)) throw new TypeError("items must be an array");
  if (typeof compare !== "function") throw new TypeError("compare must be a function");
  sortRange(items, 0, items.length - 1, compare);
  return items;
}

function sortRange(items, low, high, compare) {
  while (low < high) {
    const pivot = items[low + ((high - low) >>> 1)];
    let less = low;
    let index = low;
    let greater = high;
    while (index <= greater) {
      const order = compare(items[index], pivot);
      if (order < 0) {
        swap(items, less, index);
        less += 1;
        index += 1;
      } else if (order > 0) {
        swap(items, index, greater);
        greater -= 1;
      } else {
        index += 1;
      }
    }
    if (less - low < high - greater) {
      sortRange(items, low, less - 1, compare);
      low = greater + 1;
    } else {
      sortRange(items, greater + 1, high, compare);
      high = less - 1;
    }
  }
}

function swap(items, left, right) {
  const temporary = items[left];
  items[left] = items[right];
  items[right] = temporary;
}

function defaultCompare(left, right) {
  return left < right ? -1 : left > right ? 1 : 0;
}

const words = ["delta", "alpha", "charlie", "alpha", "bravo", "alpha"];
console.log(quickSort([...words]));
console.log(quickSort([...words], (left, right) => right.localeCompare(left)));