function getButton( e ) { if ( !e ) { e = window.event } var btn; if ( e.which ) { switch ( e.which ) { case 1: btn = 'LEFT'; break; case 3: btn = 'RIGHT'; break; } } if ( (e.button || e.button == 0) && e.which == undefined ) { switch ( e.button ) { case 0: case 2: btn = 'RIGHT'; break; case 1: btn = 'LEFT'; break; } } return btn; }