var serializationOption = {

                includeBindingSource: false, // include binding source when converting the workbook to json, default value is false

                ignoreStyle: false, // ignore styles when converting workbook to json, default value is false

                ignoreFormula: false, // ignore formulas when converting workbook to json, default value is false

                saveAsView: false, //include the format string formatting result when converting workbook to json, default value is false

                rowHeadersAsFrozenColumns: false, // treat row headers as frozen columns when converting workbook to json, default value is false

                columnHeadersAsFrozenRows: false, // treat column headers as frozen rows when converting workbook to json, default value is false

                includeAutoMergedCells: false // include the automatically merged cells to the real merged cells when converting the workbook to json.

            };

            var jsonString = JSON.stringify(spread.toJSON(serializationOption));