code: function change(evt) {
      evt = evt || win.event;
  
      if ('readystatechange' === evt.type) {
        readystate.change(docReadyState());
        if (complete !== docReadyState()) return;
      }
  
      if ('load' === evt.type) readystate.change('complete');
      else readystate.change('interactive');
  
      //
      // House keeping, remove our assigned event listeners.
      //
      (evt.type === 'load' ? win : doc)[off](evt.type, change, false);
    }
docs: Handle the various of event listener calls.
  
  @param {Event} evt Simple DOM event.
  @api private