How to know right or left click in event onclick toolbar

Hi all,
Have a nice day.
As the tile, I has a toolbar. I attach event onClick. how to know that click is left click or right click ???.

myToolbar.attachEvent(“onClick”, function(id) {
//only knew id, but not know left or right of mouse click

Unfortuntaely it is not available to recognize if the user used the left or the right mouse button in toolbar.