var http = createRequestObject();
var uid = 0;

function createRequestObject() {
var ro;
var browser = navigator.appName;
if(browser == "Microsoft Internet Explorer"){
ro = new ActiveXObject("Microsoft.XMLHTTP");
}else{
ro = new XMLHttpRequest();
}
return ro;
}

function loading(n){
uid = n;
var id = document.getElementById('provincia'+uid).value;
http.open('GET','get_comune.php?id='+id, true);
http.onreadystatechange = getComune;
http.send(null);
}

function getComune(){
var newOption;
var where = (navigator.appName == "Microsoft Internet Explorer") ? -1 : null;
var Comune = document.getElementById('comune'+uid);
while (Comune.options.length) {
Comune.remove(0);
}
id = document.getElementById('provincia'+uid).value;
if(id == '0'){
document.getElementById('comune'+uid).disabled = true;
newOption = document.createElement("option");
newOption.value = '0';
newOption.text = '-- Seleziona un Comune --';
Comune.add(newOption, where);
}else{
if(http.readyState == 4) {
if (http.status == 200) {
var response = http.responseText;
if(response == ''){
document.getElementById('comune'+uid).disabled = true;
newOption = document.createElement("option");
newOption.value = '0';
newOption.text = 'Nessuna voce';
Comune.add(newOption, where);
}else{
coppia = response.split(',');
max = coppia.length;
newOption = document.createElement("option");
newOption.value = '0';
newOption.text = '-- Seleziona un Comune --';
Comune.add(newOption, where);
for(x=0;x<max;x++){
val = coppia[x].split('-');
newOption = document.createElement("option");
newOption.value = val[0];
newOption.text = val[1];
Comune.add(newOption, where);
}
document.getElementById('comune'+uid).disabled = false;
}
}
}
}
}