Trying to Ajax woocommerce form field but have null error at console log

Question

I am trying to pass the Woocommerce form field value through ajax to WC_Session.

Based partially on "Create a Custom Shipping Method for WooCommerce" tutorial and "Dynamic shipping fee based on custom radio buttons in Woocommerce" answer thread, here is an extract of code attempt:

if ( in_array( 'woocommerce/woocommerce.php', apply_filters( 'active_plugins', get_option( 'active_plugins' ) ) ) ) {

function my_custom_shipping_method() {
        if ( ! class_exists( 'MY_Custome_Shipping_Method' ) ) {
            class my_custom_Shipping_Method extends WC_Shipping_Method {

        public function __construct() {
                    $this->id                 = 'my_custome_shipping_method';  
                    $this->method_title       = __( 'My Customize Shipping','my_custome_shipping_method' );  
                    $this->method_description = __( 'Custom Shipping Method for my custome shipping method', 'my_custome_shipping_method' );
.......
}
.......
//other shipping method code skipped
.......

public function calculate_shipping( $package = array() ) {
.......
$string = json_encode($result);
$decodedArray = json_decode($result,true);
$kekei = $decodedArray['msg'];
$balbal = array();
foreach($kekei as $goods=> $g_values) { 
    $balbal[$g_key['shipping_code'] ] = $g_values['shipping_name'];;              
}

$janggal = (array)$balbal;
WC()->session->set('janel_seesion', $balbal);
.......
}
}
}
}
}               

 add_action( 'woocommerce_shipping_init', 'my_custome_shipping_method' );

    function add_mycustome_shipping_method( $methods ) {
        $methods[] = 'My_Custome_Shipping_Method';
        return $methods;
    }

    add_filter( 'woocommerce_shipping_methods', 'add_mycustome_shipping_method' );


// Enabling delivery options for a specific defined shipping method
function targeted_shipping_method(){
    // HERE below define the shipping method Id that enable the custom delivery options
    //return 'local_pickup:5';
    return 'my_custome_shipping_method';
}

// Customizing Woocommerce checkout radio form field
add_action( 'woocommerce_form_field_radio', 'custom_form_field_radio', 20, 4 );
function custom_form_field_radio( $field, $key, $args, $value ) {
    if ( ! empty( $args['options'] ) && is_checkout() ) {
        $field = str_replace( '</label><input ', '</label><br><input ', $field );
        $field = str_replace( '<label ', '<label style="display:inline;margin-left:8px;" ', $field );
    }
    return $field;
}

add_action( 'woocommerce_review_order_after_shipping', 'custom_shipping_radio_button', 20);

function custom_shipping_radio_button() {

$domain = 'woocommerce';

if (  WC()->session->get( 'chosen_shipping_methods' )[0] == targeted_shipping_method() ) :


echo '<tr class="delivery-radio"><th>' . __('Delivery options', $domain) . '</th><td>';
$hariharikarl = WC()->session->get( 'janel_seesion' );
$chosen = WC()->session->get('chosen_delivery');
$chosen = empty($chosen) ? WC()->checkout->get_value('delivery') : $chosen;
$chosen = empty($chosen) ? 'regular' : $chosen;

// Add a custom checkbox field
woocommerce_form_field( 'radio_delivery', array(
    'type' => 'radio',
    'class' => array( 'form-row-wide' ),
    /*
    'options' => array(
    'regular' => __('Regular', $domain),
    'premium' => __('Premium +'.wc_price(2.00), $domain),
    'big' => __('Big +'.wc_price(3.00), $domain),
    'small' => __('Big +'.wc_price(5.00), $domain),

    */
    'options' => $hariharikari,
    'default' => $chosen,
), $chosen );

echo '</td></tr>';

endif;
}


// jQuery - Ajax script
add_action( 'wp_footer', 'checkout_delivery_script' );
function checkout_delivery_script() {
    // Only checkout page
    if ( ! is_checkout() ) return;
    ?>
    <script type="text/javascript">
    jQuery( function($){
        if (typeof wc_checkout_params === 'undefined')
            return false;

        $('form.checkout').on('change', 'input[name=radio_delivery]', function(e){
            e.preventDefault();
            var d = $(this).val();
            $.ajax({
                type: 'POST',
                url: wc_checkout_params.ajax_url,
                data: {
                    'action': 'delivery',
                    'delivery': d,
                },
                success: function (result) {
                    $('body').trigger('update_checkout');
                    console.log(result); // just for testing | TO BE REMOVED
                },
                error: function(error){
                    console.log(error); // just for testing | TO BE REMOVED
                }
            });
        });
    });
    </script>
    <?php

}

// Get Ajax request and saving to WC session
add_action( 'wp_ajax_delivery', 'wc_get_delivery_ajax_data' );
add_action( 'wp_ajax_nopriv_delivery', 'wc_get_delivery_ajax_data' );
function wc_get_delivery_ajax_data() {
    if ( isset($_POST['delivery']) ){
        WC()->session->set('chosen_delivery', sanitize_key( $_POST['delivery'] ) );
        echo json_encode( $delivery ); // Return the value to jQuery
    }
    die();
}

// Add a custom dynamic delivery fee
add_action( 'woocommerce_cart_calculate_fees', 'add_packaging_fee', 20, 1 );
function add_packaging_fee( $cart ) {

    if ( is_admin() && ! defined( 'DOING_AJAX' ) )
        return;

    // Only for targeted shipping method
    if (  WC()->session->get( 'chosen_shipping_methods' )[0] != targeted_shipping_method() )
        return;

    if( WC()->session->get( 'chosen_delivery' ) == 'regular' )
        $cart->add_fee( __( 'Delivery fee', 'woocommerce' ), 2.00 );

    if( WC()->session->get( 'chosen_delivery' ) == 'big' )
        $cart->add_fee( __( 'Delivery fee', 'woocommerce' ), 3.00 );



}

When I click the radio button I got null at console log and also the radio black dot is missing and did not stay at the same spot.

Also how am I gonna populate the last code above according from array that I have generated in my shipping methods foreach loop?

Any help is appreciated.