      var prop = properties[key].toString();
                if (CheckSortableProperty(prop)) {
                    if (CheckUnsortableProperty(prop)) {
                        (function (prop) {
                            // Do a Ajax call for each property to check if it is sortable
                            var request = new XMLHttpRequest();
                            var restUrl = _spPageContextInfo.webAbsoluteUrl + "/_api/search/query?querytext='*'&sortlist='" + properties[key] +":ascending'&RowLi