//Calcula el nš de noches a partir de la fecha de entrada y de salida.

 function Right(str, n){
     if (n <= 0)
        return "";
     else if (n > String(str).length)
        return str;
     else {
        var iLen = String(str).length;
        return String(str).substring(iLen, iLen - n);
     }
 }
 function Left(str, n){
     if (n <= 0)
         return "";
     else if (n > String(str).length)
         return str;
     else
         return String(str).substring(0,n);
 }

function getNights(obj_name_day_ini, obj_name_month_ini, obj_name_day_end, obj_name_month_end, obj_name_nights)
{
	var obj_day_ini = document.getElementById(obj_name_day_ini);
	var obj_month_ini = document.getElementById(obj_name_month_ini);
	var obj_day_end = document.getElementById(obj_name_day_end);
	var obj_month_end = document.getElementById(obj_name_month_end);
	
	var obj_nights = document.getElementById(obj_name_nights);
	
	var cond1 = obj_day_ini.value != "0" && obj_month_ini.value != "0";
	var cond2 = obj_day_end.value != "0" && obj_month_end.value != "0";
	
	var init_date, end_date;
	var curr_date = new Date();
	if (cond1 && cond2)
	{
		//aņo, mes-1, dia
		init_date = new Date (Left(obj_month_ini.value,4), Right(obj_month_ini.value,2), obj_day_ini.value);
		end_date = new Date (Left(obj_month_end.value,4), Right(obj_month_end.value,2), obj_day_end.value);

		var diff_date = new Date(end_date-init_date);
		obj_nights.value = parseInt(diff_date/(24*60*60*1000));
	}
}