codice:
<html>
<head>
<script type="text/javascript">
function UpdateCost(imput,tot) {
var somma;
var sum = parseFloat(tot);
var importo = parseFloat(imput.value)
if (imput.checked) {somma = (sum + importo);}
else{somma = (sum - importo);}
document.getElementById('totalcost').value = parseFloat(somma).toFixed(2);
}
</script>
</head>
<body marginheight="0" marginwidth="0">
<h1>Somma con i checkbox</h1>
<%do while not objrs.eof%>
<input type="checkbox" id='camp<%=objrs("ID")%>' value="<%=objrs("valore")%>" onclick="UpdateCost(this,document.getElementById('totalcost').value)"><%=objrs("valore")%>
<%
objrs.movenext
loop
%>
</p>
<input type="text" id="totalcost" value="0" readonly />
</p>
</body>
</html>