Click or onclick is associated with the use of a mouse on Desktop. Whereas on the likes of Mobile devices there is no mouse so for the event to fire on a object then a tap of the object on the page (screen) is required. Example If you use "Hover" on the desktop then the first mouse over will trigger the effect (colour change on a menu item) then onclick it will trigger the second go to url or page.Double-tap you mentioned; is that mean double click you meant?
The same principle applies to any object you have on the page in Desktop the onclick of the object using a mouse fires the event but on Mobile you have to tap the screen for the event to fire. Hope this explains.