socket.ref()

• 返回：<net.Socket> 套接字自身

  ¥Returns: <net.Socket> The socket itself.

与 unref() 相反，如果它是唯一剩下的套接字（默认行为），则在之前 unref 化的套接字上调用 ref() 不会让程序退出。如果套接字被 ref 再次调用 ref 将无效。

¥Opposite of unref(), calling ref() on a previously unrefed socket will not let the program exit if it's the only socket left (the default behavior). If the socket is refed calling ref again will have no effect.