jquery integration issue when attempted to execute on load
As @Kevin mentioned 


  Drupal 8.4 introduced jQuery 3.x


And according to jQuery Core 3.0 Upgrade Guide  the "ready" event has been removed.

What you should do is to implement your functional code in Drupal.behaviours. This would have the similar effect as $(document).ready() but with more benefits.

(function ($, Drupal) {

  Drupal.behaviors.myHandler = {
    attach: function (context, settings) {
      // do something
    }
  };

})(jQuery, Drupal);