Why doesn't the disconnect event from socket.io come after the internet is disconnected?

Question

Node.js

After the user disconnects the Internet, the disconnect event does not come to the server, what should I do?

Answer 1

The session is still alive, it will live the time you set or the standard time and then die, then the disconnect will occur.

Answer 2

A break in the network while the connection is open is a normal state in tcp / ip, it’s perfectly normal to open an ssh connection to the server, pull the wire out of the router, insert it in a dozen other minutes - and everything will work, even errors will not pop up (until you try to send a packet to disconnect time). This is why they came up with various timeouts ,
and socket.io itself also sends pings
periodically