Exercise 1 - Javascript Queues Question

I’m in the middle of the First Exercise for the Queues lesson and I’m failing either of the last two tests. I’m not sure I understand what this._head is supposed to be when the queue has one item but the head is empty. I thought if I dequeued everything on the collection that the head would always be zero. Why is this not the case?


If you deque everything, the head will point to null. For clear explanation kindly provide your code.