用Java Script判断用户已点选以上单选按钮

MadD

<input type="radio" name="sel" value="0" >a
<input type="radio" name="sel" value="1" >b

如何在网页作提交(Submit) 时, 用Java Script判断用户已点选以上单选按钮?

o1j2m3

<form onSubmit="return chk();" name="frm">
//...any form components
</form>
<script>
function chk() {
   if (document.frm.sel.value == "0" || document.frm.sel.value == "1" ) return true;
   return false;
}
</script>

Jasper

<input type="radio" name="sel" value="0" >a
<input type="radio" name="sel" value="1" >b

function checkClick(){
var checked=false
for(i=0; i<document.formName.sel.length; ++i)
   if(document.formName.sel[i].checked)
     checked=true
}