Single check Box Validation for Datalist in javascript

function checkBoxValidationForSingle(obj)
        {
            var list= document.getElementById("<%=DataList1.ClientID%>");
            var listlen =list.rows.length
            for(var i=0; i< listlen ; i++)
                {
                        var input=document.getElementsByTagName("input");
                        var inputlen=input.length
                        for (i=1; i<inputlen; i++) 
                         {                        
                            if(input[i].type=="checkbox")
                            {
                               if(input[i].id != obj.id)
                                 {
                                    input[i].checked=false;
                                 }
                             }
                          }
                  }
        }