调用时,只要 <fs.StatWatcher> 处于活动状态,就请求 Node.js 事件循环不退出。 多次调用 watcher.ref() 将不起作用。

    When called, requests that the Node.js event loop not exit so long as the <fs.StatWatcher> is active. Calling watcher.ref() multiple times will have no effect.

    By default, all <fs.StatWatcher> objects are "ref'ed", making it normally unnecessary to call watcher.ref() unless watcher.unref() had been called previously.