work_time-1.0.x-dev/js/work-time-keeper.js

(function ($, Drupal, drupalSettings, once) {

  Drupal.behaviors.timekeeper = {
    attach: function (context, settings) {
      const $elements = $(once('loadTimeKeeper', '.work-timekeeper', context));
      $elements.each(loadTimeSheet);
    }
  };

  function loadTimeSheet(index, month) {

  }
}(Drupal, jQuery, once));