button

Returns a button pressed during events caused by pressing or releasing one or multiple buttons. As such, it is not reliable for events such as mouseenter, mouseleave, mouseover, mouseout or mousemove.

Users may change the configuration of buttons on their pointing device so that if an event's button property is MAIN (left), it may not have been caused by the button that is physically left–most on the pointing device; however, it should behave as if the left button was clicked in the standard button layout.