fs.watch API 跨平台并非 100% 一致，并且在某些情况下不可用。
fs.watch API is not 100% consistent across platforms, and is
unavailable in some situations.
The recursive option is only supported on macOS and Windows.
ERR_FEATURE_UNAVAILABLE_ON_PLATFORM exception will be thrown
when the option is used on a platform that does not support it.
On Windows, no events will be emitted if the watched directory is moved or
EPERM error is reported when the watched directory is deleted.