let jsonObject = {"Data1":1, "Data2":"Test1"}; jsonObject["Data1"] = 100; jsonObject["NewData"] = 123; console.log(jsonObject); let jsonObject = [{"Data1":1, "Data2":"Test1"},{"Data1":2, "Data2":"Test2"}]; for (let i in jsonObject){ delete jsonObject[i]["Data1"]; console.log(jsonObject);