$.ajax({
                    url: _spPageContextInfo.webAbsoluteUrl + url,
                    type: "PATCH",
                    headers: {
                        "accept": "application/json;odata=verbose",
                        "__metadata":    {"type": "SP.Data.CaseListItem"},
                        "X-RequestDigest": $("#__REQUESTDIGEST").val(),
                        "content-Type": "application/json;odata=verbose",
                        "X-Http-Method": "PATCH",
                        "If-Match": olditem.__metadata.etag
                    },
                    data: JSON.stringify(item),
                    success: function (data) {
                        console.log(data);
                    },
                    error: function (error) {
                        console.log(JSON.stringify(error));
                    }
                });