D8 Drupal Behaviors (on page load)

(function ($, Drupal, window, document) {
  'use strict';

  // Example of Drupal behavior loaded.
  Drupal.behaviors.exampleJS = {
    attach: function (context, settings) {
      if (typeof context['location'] !== 'undefined') { // Only fire on document load.

        console.log('This is loaded');

      }
    }
  };

})(jQuery, Drupal, this);