How to detect when click on select in form and selected="" is the default but

If not choice another dispaly error message as not selected from list with jQuery?

	$('#select_touch_general').on('change', function(){
		if ($(this).is(':invalid')) {
			$('#u_touch_general').show(0).text('Choose category: is invalid');
		}
		if ($(this).is(':valid')) {
			$('#u_touch_general').hide(0);
		}
	});

Something like this but here :invalid not work any idea?

Thanks