Ajax and no Ajax WP Options Page - Multiple DB Options

ajax_and_no_ajax_wp_plugin_options_page.php

<?php

add_action('wp_ajax_save_i9_analytics_options', 'save_i9_analytics_options');
add_action('wp_ajax_nopriv_save_i9_analytics_options', 'save_i9_analytics_options');
function save_i9_analytics_options()
{
    if (!empty($_POST)) {
        $i9_heap_id             = $_POST["i9_heap_id"];
        $i9_mixpanel_id              = $_POST['i9_mixpanel_id'];
        $i9_amplitude_id              = $_POST['i9_amplitude_id'];
        update_option('i9_heap_id', $i9_heap_id);
        update_option('i9_mixpanel_id', $i9_mixpanel_id);
        update_option('i9_amplitude_id', $i9_amplitude_id);
        echo "OK";
        wp_die();
    }
    echo "ERROR";
    wp_die();
}

add_action('admin_menu', 'i9_analytics_integration');

function i9_analytics_integration()
{
    add_menu_page('i9 Analytics Integration Settings', 'i9 Analytics Integration', 'administrator', __FILE__, 'i9_analytics_integration_options_page', plugins_url('/images/icon.png', __FILE__));
    add_action('admin_init', 'register_i9_analytics_integration_settings');
}


function register_i9_analytics_integration_settings()
{
    //register our settings
    register_setting('i9-analytics-integration-group', 'i9_heap_id');
    register_setting('i9-analytics-integration-group', 'i9_mixpanel_id');
    register_setting('i9-analytics-integration-group', 'i9_amplitude_id');
}

function i9_analytics_integration_options_page()
{
    ?>
    <div class="wrap">
        <h1>i9 Analytics Integration</h1>

        <form id="i9_analytics" method="post" action="options.php">
            <?php settings_fields('i9-analytics-integration-group'); ?>
            <?php do_settings_sections('i9-analytics-integration-group'); ?>
            <table class="form-table">
                <tr valign="top">
                    <th scope="row">Heap ID</th>
                    <td><input type="text" name="i9_heap_id" value="<?php echo esc_attr(get_option('i9_heap_id')); ?>" /></td>
                </tr>

                <tr valign="top">
                    <th scope="row">MixPanel ID</th>
                    <td><input type="text" name="i9_mixpanel_id" value="<?php echo esc_attr(get_option('i9_mixpanel_id')); ?>" /></td>
                </tr>

                <tr valign="top">
                    <th scope="row">Amplitude ID</th>
                    <td><input type="text" name="i9_amplitude_id" value="<?php echo esc_attr(get_option('i9_amplitude_id')); ?>" /></td>
                </tr>
            </table>
            <?php submit_button(); ?>
            <span id="message"></span>

            <script>
                jQuery('#i9_analytics').on('submit', (e) => {
                    jQuery('#message').html('Saving').show();
                    e.preventDefault();
                    let formdata = jQuery("#i9_analytics").serializeArray();
                    let data = {};
                    jQuery(formdata).each((index, obj) => {
                        data[obj.name] = obj.value;
                    });
                    
                    let postData = {
                        action: 'save_i9_analytics_options',
                    };
                    Object.assign(data, postData);
                    jQuery.post(ajaxurl, data).done(() => {
                        jQuery('#message').html('General Settings Saved').fadeOut(0).fadeIn(200);
                    }).fail((err) => {
                        jQuery('#message').html('Error: ' + JSON.stringify(err)).fadeOut(0).fadeIn(200);
                    });
                })
            </script>

        </form>
    </div>
<?php } ?>