Never mind, I worked out a a solution.
Using for(var propertyName in rs.rows.item(0)) I could see that the property is count(*), so ” rs.rows.item(0).count(*)” is illegal so the workaround is to label the resultset using something like:
SELECT count(*) as count FROM items
so you can use rs.rows.item(0).count
Hope this helps someone, one day.