$.ajax({
        type: "POST",
        url:url,
        contentType: "application/json",
        processData: false,
        data: JSON.stringify({
                start_date:   scheduler.getEvent(id).start_date,
                end_date:  scheduler.getEvent(id).end_date,
                text: scheduler.getEvent(id).text,
                userId: userId
        }),
        success:function(result){
         //here some code
        }
    });