Node.js/socket.io "global" variable

Question

I have an application that allows two users to connect to a websocket (which is written in node.js using socket.io). Imagine that the users can deduct a number from 20 (which is defined by the server), each of the two users can do the deduction in a turn-by-turn basis.

My question is, how/where should I setup the 'global' variable of 20? At the moment I set it up when a client connects to the socket but that's incorrect because if we have user 1 connected and he has removed '5' then user 2 (connecting later) should only see that the max number is 15 instead of 20, with my current method user 2 will also see 20. Should I create my varialbe and assign the value '20' to it when I create the http server?

Are you really just storing a number? Do you need to have multiple servers reading/writing from this state? — Brad
– Brad, Commented Apr 29, 2013 at 4:04
at the moment I'd like to keep things simple (still learning nodejs/socket.io) so there is one server with 2 clients. — Tamas
– Tamas, Commented Apr 29, 2013 at 4:04

Brad · Accepted Answer · 2013-04-29 14:23:02Z

2

Nothing special is needed for this. It doesn't even have to be global. Just keep it outside of the functions handling the clients' requests.

var sharedNumber = 20;

socket.on('subtractNumber', function (number) {
    sharedNumber -= number;
    return sharedNumber;
});

socket.on('getNumber', function () {
    return sharedNumber;
});

answered Apr 29, 2013 at 14:23

Brad

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