var XMLHttpReq;
function abrir(url, local, mensagem)
{
    getXMLHttpRequest();
    XMLHttpReq.onreadystatechange = function(){
        if(mensagem){
            if(XMLHttpReq.readyState==1){
                window.document.getElementById(local).innerHTML="<div style='font-style:italic; color:#FFFFFF; background-color:#00FF00; line-height:20px; width:80px; float:right; text-align:center'>Carregando...</div>";
            }
        }
        if(XMLHttpReq.readyState==4){
            window.document.getElementById(local).innerHTML=XMLHttpReq.responseText;
        }
    }
    XMLHttpReq.open("GET", url, true);
    XMLHttpReq.send(null);
}

function getXMLHttpRequest(){
    if(window.XMLHttpRequest){
        XMLHttpReq = new XMLHttpRequest();
    }else if(window.ActiveXObject){
        XMLHttpReq = new ActiveXObject("Microsoft.XMLHTTP");
    }else{
        window.alert("Seu navegador não suporta XMLHTTP.\nUtilize outro navegador para navegar neste site.");
    }
}

function carregaCalendario(){
    var url = "calendario.php?req=1&cidade="+document.getElementById("cidade").value;
    abrir(url, "coleta", true);
}