Ninja Forms submit:response

plugin.php

<?php

/**
 * Plugin Name: Ninja Forms Sandbox
 */

add_action( 'wp_enqueue_scripts', function() {
    wp_enqueue_script('ninja_forms_display_sandbox', plugin_dir_url(__FILE__) . 'script.js', ['nf-front-end'], time() );
});

script.js

// Create a new object for custom validation of a custom field.
var mySubmitController = Marionette.Object.extend( {

  initialize: function() {
    console.log('Controller loaded');
    this.listenTo( Backbone.Radio.channel( 'forms' ), 'submit:response', this.actionSubmit );
  },

  actionSubmit: function( response ) {
    console.log('Form Submitted');
  },

});

// On Document Ready...
jQuery( document ).ready( function( $ ) {
  console.log('Document ready.');
  // Instantiate our custom field's controller, defined above.
  new mySubmitController();
});

console.log('Script enqueued');