我用循环生成了100组radiobutton按钮，每组7个，请问如何判断那个radiobutton被选中？

var cc = document.getElementsByTagName("input");
                     for(var j=0;j<cc.length;j++)
                    {
                        if(cc[j].type=="checkbox")
                        {
                             if(cc[j].checked==true)
                            {
                             //turtu
                                
                             }
                        }
                     }