Client-Side:

$('form').submit(function (e) {
	e.preventDefault();
	$.post(
		//placeholder text
			$.ajax({
				var s2 = true;
				type: 'POST',
				url: '/add',
				data: {NEWDATA : DATA_OBJECT_TO_BE_SENT_BACK_TO_SERVER},
				dataType: "jsonp"
			});
		}
	);
});

Server-Side:

app.post('/', function (req, res) {
	var placeholder = 1;

	res.send({placeholder : placeholder});

	if (s2) {
		function (data) {
			console.log(data.NEWDATA);
		}
	}
});