Add a 'disconnecting' event to access to socket.rooms upon disconnection

[darrachequesne]

As suggested there #1814 (all credits to @X-Coder)

socket.on('disconnecting', function(){
  var rooms = socket.rooms.slice();
  // socket.rooms should not be empty here (on 'disconnect' it is, because `leaveAll()` has already been called)
});

[nkzawa]

👍

Alternatively, we would be able to emit disconnect event before leaving rooms, in a similar way to the followings.

https://github.com/socketio/engine.io/blob/master/lib/socket.js#L296
https://github.com/socketio/engine.io-client/blob/master/lib/socket.js#L708

Though disconnecting event looks better to me too.

[rauchg]

Let's resume this discussion after 1.4.0

[phutchins]

+1 on disconnecting. I have a branch that I was going to create a PR from that looks nearly identical to this... :)

I could also see renaming disconnect to disconnected but that would be a breaking change for a lot of folks... It would clear up what event you're actually catching however and might be worth it.

[kgunbin]

+1

[enjikaka]

Merge it!

[Alexandre-io]

+1

[Arcanorum]

+1 Cmon guys, make it happen...

[Walraz]

+1 This feature must exist now!

[slhrkc]

+1

[gaurav21r]

+1 ! @rauchg I guess we are at 1.4.8 now! Can you please take a look at this? I guess this is a very common use case!

[OmarElgabry]

+1

[FrederikBolding]

+1

[AndreasGassmann]

+1

[enjikaka]

Finally. Great! 💃

[X-Coder]

Thank you, finally no more +1 mails in my inbox :-)
Did I miss the party? You merged it on the second birthday of the initial #1814 issue post.