quickSort.js

function QuickSort(arr, left = 0, right = arr.length - 1) {
	let len = arr.length,
		index;

	if (len > 1) {
		index = partition(arr, left, right);

		if (left < index - 1) {
			QuickSort(arr, left, index - 1);
		}

		if (index < right) {
			QuickSort(arr, index, right);
		}
	}

	return arr;
}

function partition(arr, left, right) {
	let middle = Math.floor((right + left) / 2),
		pivot = arr[middle],
		i = left, // Start pointer at the first item in the array
		j = right; // Start pointer at the last item in the array

	while (i <= j) {
		// Move left pointer to the right until the value at the
		// left is greater than the pivot value
		while (arr[i] < pivot) {
			i++;
		}

		// Move right pointer to the left until the value at the
		// right is less than the pivot value
		while (arr[j] > pivot) {
			j--;
		}

		// If the left pointer is less than or equal to the
		// right pointer, then swap values
		if (i <= j) {
			[arr[i], arr[j]] = [arr[j], arr[i]]; // ES6 destructuring swap
			i++;
			j--;
		}
	}

	return i;
}