Get which radio button is selected

 function Check()
    {
    alert('a');
    var radios=document['form1'].elements['n'];
    for(var i=0;i<radios.length;i++)
    {
    
     if(radios[i].checked==true)
     {
      alert('Checked');
     alert(radios[i].value);
     }
   
    }
    }