codice:
<!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>
<title>Pagina senza titolo</title>
<script language="javascript" type="text/javascript">
// <!CDATA[
function funzione()
{
var risultato = 0;
for(var i = 1; i <= 2; i++)
{
var v = document.getElementById("vote" + i).value;
risultato += parseInt(v, 10);
}
if(!isNaN(risultato))
document.getElementById("risultato").value = risultato;
else
document.getElementById("risultato").value = "Completa la votazione";
}
// ]]>
</script>
</head>
<body>
<select id="vote1" onchange="funzione();">
<option value="" selected="selected">Vote</option>
<option value="1">1</option>
<option value="2">2</option>
<option value="3">3</option>
<option value="4">4</option>
<option value="5">5</option>
<option value="6">6</option>
<option value="7">7</option>
<option value="8">8</option>
<option value="9">9</option>
<option value="10">10</option>
</select>
<select id="vote2" onchange="funzione();">
<option value="" selected="selected">Vote</option>
<option value="1">1</option>
<option value="2">2</option>
<option value="3">3</option>
<option value="4">4</option>
<option value="5">5</option>
<option value="6">6</option>
<option value="7">7</option>
<option value="8">8</option>
<option value="9">9</option>
<option value="10">10</option>
</select>
<input id="risultato" type="text" size="5" maxlength="5" disabled="disabled" value="qui dovrebbe comparire la somma!"/>
</body>
</html>