I don't know if I use button id jquery ajax serialize right, but doesn't work

Question

$('button.red-button').on('click', function(form)
            {
                form.preventDefault();

                var obj = {};
                obj.id = $(this).attr('id');
                //var id['id'] = $(this).attr('id');
                alert(JSON.stringify(obj));
                $.ajax(
                {
                    type: 'POST',
                    dataType: 'json',
                    url: 'delete-comment',
                    data: JSON.stringify(obj),
                    success: function(data)
                    {
                        alert(data);
                    },
                    error: function(data)
                    {
                        alert(0);
                    }
                });
            });

This is what I made.

For example we have this button

<button id="4" class="red-button">Usuń</button>

This script will alert first

{"id":"4"}

So it alerts it's ID in JSON format.

This is what i wanted, to delete this item by doing AJAX POST request.

But in PHP by doing

echo json_encode($this->input->post('id'));

I got NULL in second alert.

or

echo json_encode($_POST['id']);

and i got 0 in second alert

I'm doing something wrong but I don't know... Maybe this json is send wrongly, or json is build wrongly idk

Answer 1

$('button.red-button').on('click', function(form)
        {
            form.preventDefault();

            var obj = {};
            obj.id = $(this).attr('id');
            //var id['id'] = $(this).attr('id');
            alert(JSON.stringify(obj));
            $.ajax(
            {
                type: 'POST',
                dataType: 'json',
                url: 'delete-comment',
                data: obj,
                success: function(data)
                {
                    alert(data);
                },
                error: function(data)
                {
                    alert(0);
                }
            });
        });

Use it like that and it will work, without stringify the object