Qualcosa del genere?
codice:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<title>Conta le checkbox attive</title>
<script language="javascript" type="text/javascript">
<!--
var init = 0;
function count(caller, target) {
if (caller.checked) {
init++;
}
else {
init--;
}
document.getElementById(target).value=init;
}
-->
</script>
</head>
<body>
<form name="checkboxes">
<input type="checkbox" onClick="count(this, 'textfield')" value="prima">
Prima
<input type="checkbox" onClick="count(this, 'textfield');" value="Seconda">
Seconda
<input type="checkbox" onClick="count(this, 'textfield');" value="Terza">
Terza
<input type="checkbox" onClick="count(this, 'textfield');" value="Quarta">
Quarta
<input type="checkbox" onClick="count(this, 'textfield');" value="Quinta">
Quinta</p>
Numero di checkboxes selezionate:
<input type="text" id="textfield">
</p>
</form>
</body>
</html>