And what about the middle?

The middle needs to stay above the bottom. Please find the code attached to see the core conditional logic put together.

xxxxxxxxxx

if (arr[mid] === 0) {

  swap(arr, low++, mid++);

} else if (arr[mid] === 2) {

  swap(arr, mid, high--);

} else if (arr[mid] === 1) {

  mid++;

}