notify = message => {

  // @todo add to environment
  const notifyTiddlerRef = '$:/temp/tiddlymap/notify';

  $tw.wiki.addTiddler(new $tw.Tiddler({
    title : notifyTiddlerRef,
    text : message
  }));

  $tw.notifier.display(notifyTiddlerRef);

}
This function uses the tw-notification mechanism to display a
temporary message.

@see https://github.com/Jermolene/TiddlyWiki5/blob/master/core/modules/utils/dom/notifier.js
@param {string} message - A short message to display.