How can retrieve last item values in a list

Good day
How i can retrieve the last item in a list ?
I have a list with requests vacation. On approve I need to put internal number, which must be in sequence. like 1,2,3. Items can be approved in different time, for example item with internal SharePoint ID 1, can be approved after item with SharePoint ID=10.
that's why i thought about storing on approve, item internal number in a separate list. Then in another item of vacation i must retrieve this last internal number. then give it +1 ,and write in current item.

Could you not get the list items and use the object length to determine?

Could you please send me an example

var list = pnp.sp.web.lists.getByTitle('YourListName');
var myID = items.length;

If you every delete items from the target list you could sort the resulting items like:
items.sort((firstItem, secondItem) => firstItem.ID - secondItem.ID);

The largest ID should be the last item in your array. So you could get that value by:

var lastID = items[items.length + 1].ID;

thank you.
as a result i have length of list - 18 items. but the last item ID is 54 for example:

On sort items i have an error:

Do you know some else methods?

@ixxxl ,
I am not at a computer today, maybe try logging the items and see what the ID field comes in. It may be called Id. Just a thought.