server.unref()

• Returns: <net.Server>

如果这个server在事件系统中是唯一有效的，那么对server调用unref将允许程序退出。如果这个server已经调用过unref那么再次调用将不会再有效果。

• Returns: <net.Server>

Calling unref() on a server will allow the program to exit if this is the only active server in the event system. If the server is already unrefed calling unref() again will have no effect.