Ti invio il codice sorgente html:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<script type="text/javascript" src="js/jquery.min.js"></script>
<title>Disponibilità</title>
</head>

<body>

<script type="text/javascript">
var xmlhttp;

function mostraInfo(str)
{
xmlhttp=GetXmlHttpObject();
if (xmlhttp==null)
{
alert ("Browser does not support HTTP Request");
return;
}
var url="#";
url=url+"?q="+str;
xmlhttp.onreadystatechange=stateChanged;
xmlhttp.open("GET",url,true);
xmlhttp.send(null);
}

function stateChanged()
{
if (xmlhttp.readyState==4)
{
document.getElementById("info").innerHTML=xmlhttp. responseText;
}
}

function GetXmlHttpObject()
{
if (window.XMLHttpRequest)
{
// code for IE7+, Firefox, Chrome, Opera, Safari
return new XMLHttpRequest();
}
if (window.ActiveXObject)
{
// code for IE6, IE5
return new ActiveXObject("Microsoft.XMLHTTP");
}
return null;
}
</script>





<form action="#" method="POST" id="formut">

<h1>Medico</h1>

Seleziona giorno:
<select name="scelta" onChange="mostraInfo(this.value)">

<option value='1'>Luned&igrave </option><option value='2'>Marted&igrave </option><option value='3'>Mercoled&igrave </option><option value='4'>Gioved&igrave </option><option value='5'>Venerd&igrave </option><option value='6'>Sabato </option><option value='7'>Domenica </option> </select>

</form>



Notice: Undefined index: scelta in C:\xampp\htdocs\LDM\dispon.php on line 78

hai scelto questo valore
</body>
</html>