javascript循环判断Radio是否选中

function CheckRadioButton(){     
      var temp=document.getElementsByName("radiobutton");
      var Checked=false;
      for (i=0;i<temp.length;i++){
        if(temp[i].checked)
        {
           Checked=true;
           break;
        }
        else
        {
            Checked=false;
        }
      }
      if(Checked==false)
      {
        alert('Please select your favourite team.');
        return false;
      }
    }