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Properly getting a socket by ID #503

tommedema opened this Issue Sep 2, 2011 · 16 comments


None yet

I've asked on IRC what the proper way is to get a socket by id from the normal namespace. Supposedly it would be io.sockets.client(id). Unfortunately, this method does not exist. I figured it'd be a typo, and it should be io.sockets.clients(id). However, the clients method expects a room and then returns an array of all sockets in that room.

Thus, one could get a socket by id like so:

function getSocketById(id) {
    var clients = io.sockets.clients(),
        client  = null;
    clients.forEach(function(_client) {
        if (_client.id === id) return (client = _client);
    return client;

This is obviously rather excessive. A much more efficient way would be to access the socket by id through a library (an object where id is the key).

From the source, another way to access a socket by id is io.sockets.socket(id);. Unfortunately, there are 2 problems here:

  • the method is flagged private
  • the method creates a new socket when the given id does not exist

Thus, this method cannot be used as passing an invalid or non-existant id would trigger the creation of a dead socket.

Is there no proper way to get a client from a namespace by id at the moment?


3rd-Eden commented Sep 2, 2011

It was actually io.sockets.socket see https://github.com/LearnBoost/socket.io/blob/master/lib/namespace.js#L202 I could have sworn it was .client().

And it will indeed generate a new client, but there isnt any other way of doing it.. except for looking in the interal client object, which isn't adviced

@3rd-Eden, please read my entire post ;) I did address io.sockets.socket and it has its own issues. Thanks.


3rd-Eden commented Sep 2, 2011

@tommedema I noticed that part as was already editing my reply :)

Closing this as proper scalable solutions are in the works!

@tommedema tommedema closed this Sep 2, 2011

@tommedema, can you share your proper scalable solution?

@pyrostrex, I'm afraid you misunderstood me. I do not have such solution yet. :)

@tommedema, owh XD. my bad.

If the solution is not there yet, the issue shouldn't be closed.

Can this be re-opened please? There is still no way to easily get a socket by ID without running the risk of creating new sockets.

bijanv commented Dec 28, 2012

Going to add in a request to re-open this as well! Would be a very useful addition

I think you can use the io.sockets.sockets property as a hash to get the socket by id like this:

var socket = io.sockets.sockets[socket_id];

contra commented Apr 11, 2013

Is there a scalable way to do this yet?

For socket.io version 1.0.6, I think you can use this:
var socket = io.sockets.connected[socket.id];

For socket.io version 1.0.6, I think you can use this:
var socket = io.sockets.connected[socket.id];

just as a data point, this doesn't work as of socket.io 1.2.x

io.sockets.sockets is an array of sockets, so you can

var socket = _.findWhere(io.sockets.sockets, {id: 'mySocketId'});

using underscore or

var socket;
for (var i = 0; i < io.sockets.sockets; i += 1) {
  if (io.sockets.sockets[i].id === 'mySocketId') {
    socket = io.sockets.sockets[i];

more general. Have in mind that io.sockets is the "/" namespace. For specific namespace: io.of('/ns').sockets.

@romelperez thanks man, that was super helpful, old app stopped working after upgrade because this doesn't work anymore: var socket = io.sockets.sockets[socket_id];, saludos

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