How to check how many participants are connected to my chat room using socket IO

Question

Here is an excerpt of the code I am using to make a connection to my chat room...

io.on('connection', function(socket) {
    var col = db.collection('messages');
    sendStatus = function(s){
        socket.emit('status', s);
    };
    //emit all messages
    col.find().limit(100).sort({_id:1}).toArray(function(err, res){
        if(err) throw err;
        socket.emit('output', res);

    });
    socket.on('input', function(data) {
    ...
    ... etc

What code can I implement to check how many users or participants are connected to my chat room.

I heard of a method clients() but I'm not sure if that's what I need to use or how to use it.

Answer 1

In the latest version of socket.io, you can see how many sockets are in a given chat room with this:

io.sockets.adapter.rooms["testRoom"].length

Where testRoomis whatever the name of your chat room is (whatever you used .join() with.

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io.sockets.adapter.rooms["testRoom"]

is an Object where each property name except .length is the socket.id of the socket that is in the chat room.

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FYI, the code you show in your question doesn't appear to have anything to do with socket.io chat rooms so that has me a bit perplexed.