Ajax doesn't work after using _remap

Hi
I have added _remap() function in controller because I need to pass parameter in index, also index should work without passing parameter inside.
Example with passed parameter in url: mywebsite.com/history/12
Example without parameter in url: mywebsite.com/history
Both examples are working with _remap() function in controller !

Now issue that I have is that when I want to use ajax and call function in same controller it doesn't work, I get returned whole page content, but when I remove _remap() from controller then this examples mentioned above is not working, but ajax working. How this can be fixed ?

Controller

PHP Code:

<?php
defined('BASEPATH') OR exit('No direct script access allowed');

class History extends MY_Customcontroller {

    function __construct()
    {
        parent::__construct();
    }

    public function _remap($id)
    {
        $this->index($id);
    }

    public function index($id = null)
    {
        $this->load->view('templates/header');
        if ($id == null) {
            // error, load other view
        } else {
            $this->load->view('history');
        }
        $this->load->view('templates/footer');
    }

    // Get history list through ajax
    public function get_history($id)
    {
        $data = array();

        $mem_data = $this->orders_model->make_datatables();

        foreach ($mem_data as $order) {
            $data[] = array(
                $order->ticket_status,
                $order->symbol != '' && strlen($order->symbol) > 6 ? substr($order->symbol, 0, 6) : $order->symbol,
                $order->order_type,
                date('Y-m-d H:i', strtotime($order->open_time)),
                number_format($order->open_price, 2, '.', ','),
                number_format($order->lot_size, 2, '.', ','),
                number_format($order->stop_loss, 2, '.', ','),
                number_format($order->take_profit, 2, '.', ','),
                $order->close_time == '1970-01-01 00:00:00' ? 'N/A' : date('Y-m-d H:i', strtotime($order->close_time)),
                number_format($order->close_price, 2, '.', ','),
                number_format($order->profit, 2, '.', ',')
            );
        }

        $output = array(
            'draw' => $_POST['draw'],
            'recordsTotal' => $this->orders_model->get_all_data(),
            'recordsFiltered' => $this->orders_model->get_filtered_data($_POST),
            'data' => $data
        );

        echo json_encode($output);
    }
} 


View

PHP Code:

<script>
var user_id = '<?php echo $this->uri->segment('2'); ?>';

$.ajax({
    url: '<?php echo base_url('history/get_history/'); ?>'+user_id,
    type: 'post',
    success: function(response) {
        console.log(response)
    }
});
</script>