diffDates.js

$('input.salida').change(function(event) {
	if ($('input.llegada').val() != '' && $(this).val() != '') {
		var fechaI = $('input.llegada').val().split('/');
		var date1 = new Date(fechaI[2], (fechaI[1] - 1), fechaI[0], 0, 0, 0, 0); 
		var fechaF = $(this).val().split('/');
		var date2 = new Date(fechaF[2], (fechaF[1] - 1), fechaF[0], 0, 0, 0, 0);
		var timeDiff = Math.abs(date2.getTime() - date1.getTime());
		var diffDays = Math.ceil(timeDiff / (1000 * 3600 * 24)); 
		$('input.noches').val(diffDays);
	}
});