function NAjax(){

    var url = "http://www.iguania.com/iguania.inc.php/calendario.php?" + document.getElementById('next').value;
	
    http.open("GET", url, true);

    http.onreadystatechange = AAjax;

    http.send(null);

}

function PAjax(){
	
    var url = "http://www.iguania.com/iguania.inc.php/calendario.php?" + document.getElementById('prev').value;
	
    http.open("GET", url, true);

    http.onreadystatechange = AAjax;

    http.send(null);
	
}

function AAjax(){

    if(http.readyState == 4){

    document.getElementById('calendario').innerHTML = http.responseText;

    }

}