<html>
<head>
<script>
function alert_which_radio_button(f) {
if (f.val[0].checked) alert("you chose 1");
if (f.val[1].checked) alert("you chose 2");
if (f.val[2].checked) alert("you chose 3");
if (f.val[3].checked) alert("you chose 4");
if (f.val[4].checked) alert("you chose 5");
}
</script>
</head>
<body>
<form name='frm'>
<input name='val' type='radio' value='1' checked> 1
<br><input name='val' type='radio' value='2'> 2
<br><input name='val' type='radio' value='3'> 3
<br><input name='val' type='radio' value='4'> 4
<br><input name='val' type='radio' value='5'> 5
<p><input type='button' value='check' onClick='alert_which_radio_button(frm);'>
</form>
</body>
</html>