dataGrid無法通過js來控制readonly，如果是要控制輸入項，您可以參考：

//修改時，欄位不可編輯。寫在DataGrid onUpdate事件

function UpdateTest() {

            var row = $(dgid).datagrid('getSelected');

            var index = $(dgid).datagrid('getRowIndex', row);

            var editIndex = undefined;

            if (editIndex != index) {

                    $(dgid).datagrid('selectRow', index).datagrid('beginEdit', index);

                    var cellEdit = $(dgid).datagrid('getEditor', { index: index, field: 'FieldName' });

                       $(cellEdit.target).attr("disabled", "disabled"); //text

                       //$(cellEdit.target).combobox('disable'); //combobox

                       //$(cellEdit.target).datebox({ disabled: true }); //datebox

                       //$(cellEdit.target).refval('disable'); //refval

            }            

        }

//新增時，欄位不可編輯。在DataGrid toolItem新增一個按鈕

function InsertTest() {            

            var index = $(dgid).datagrid('getRows').length;

            insertItem(dgid, "$(this)"); //--新增空白一筆記錄

            var editIndex = undefined;

            if (editIndex != index) {

                $(dgid).datagrid('selectRow', index).datagrid('beginEdit', index);

                var cellEdit = $(dgid).datagrid('getEditor', { index: index, field: 'FieldName' });;

                $(cellEdit.target).attr("disabled", "disabled"); //text

                //$(cellEdit.target).combobox('disable'); //combobox

                //$(cellEdit.target).datebox({ disabled: true }); //datebox

                //$(cellEdit.target).refval('disable'); //refval

            }

}