How do I determine if a radio button was chosen on a form?

[Sue K]

I need to verify that a radio button was chosen on a form prior to the form being validated by our server's CGI routine. I'd like to issue an alert if the radio button was not chosen. How do I do this using Javascript???

Thanks!!

[johneboy]

<script language="javascript">
function validateForm(){
if(document.getElementById('rOpt').checked==true){return true;}else{alert('select radio option');return false;}
}
</script>
<form name=form>
<input type="radio" name="rOpt">Radio Option
<input type="submit" onclick="validateForm();return">
</form>