Hongtting

<input type="radio" name="class" value="1">
<input type="radio" name="class" value="2">
<input type="radio" name="class" value="3">
<input type="radio" name="class" value="4">

<script>
var inputRadio = document.getElementsByName('class');
var inputRadioCnt = document.getElementsByName('class').length;
var isRadioChecked = 0;

for(var i=0; i<inputRadioCnt; i++)
{
       if(inputRadio[i].checked) 
        {
         isRadioChecked++;
        }
}


if(isRadioChecked < 1)
{
 alert('RADIO 버튼을 선택하세요');
}
</script>


어디선가 줍어온 TIP 입니다. 기억이 나지 않음 !!