Best way of handling socket.io events in node.js

Implementing a simple turn-based board game in node using websockets and my design for this is starting to look a little messy.

Basically i have the following questions

• handle reconnects?? on connect im mapping socket ID -> express session ID... deleting it on disconnect and remapping on connect again.
• Cleaning up inactive users, i.e. user has been disconnected for n time.
• Nesting all socket event listeners inside on('connection')?? is there an alternative/what are pros/cons of it.

It just seems like too much manual tracking of state where i'm likely to miss something as it gets more complex, is there a cleaner way of handling this

  class GameManager {
    constructor(io) {
        let self = this;
        self.io = io;
        self.lfg = {};
        self.games = {};
        //socket ID -> session ID
        self.sockets = {}
        //sessionID -> gameID
        self.disconnected = {};
        io.sockets.on('connection', function (socket) {
            let sessionID = getSessionID(socket);
            self.sockets[socket.id] = sessionID;
            this.reconnect(sessionID);
            socket.on('disconnect', this.disconnect);
            socket.on('findMatch', this.findMatch);
        });
    }

    disconnect(socket) {
        let sessionID = this.sockets[socket.id];
        delete this.sockets(socket.id);
        //only add user if they were in-game
        self.disconnected[sessionID] = game ID
    }

    findMatch(socket){
        //match user in lfg, create new game, place users into socket room
    }

    reconnect(sessionID){
        if (sessionID in this.disconnected) {
            delete this.disconnected[sessionID];
            //remove disconnected expiry
        }
    }
}