websocket - webSocketServer node.js how to differentiate clients

Question

I am trying to use sockets with node.js, I succeded but I don't know how to differentiate clients in my code. The part concerning sockets is this:

var WebSocketServer = require('ws').Server, 
    wss = new WebSocketServer({port: 8080});
wss.on('connection', function(ws) {
    ws.on('message', function(message) {
        console.log('received: %s', message); 
        ws.send(message);
    });
    ws.send('something');
});

This code works fine with my client js.

But I would like to send a message to a particular user or all users having sockets open on my server.

In my case I send a message as a client and I receive a response but the others user show nothing.

I would like for example user1 sends a message to the server via webSocket and I send a notification to user2 who has his socket open.

Answer 1

In nodejs you can directly modify the ws client and add custom attributes for each client separately. Also you have a global variable wss.clients and can be used anywhere. Please try the next code and try to connect at leat two clients:

var WebSocketServer = require('ws').Server;
var wss = new WebSocketServer({
    server: httpsServer
});


wss.getUniqueID = function () {
    function s4() {
        return Math.floor((1 + Math.random()) * 0x10000).toString(16).substring(1);
    }
    return s4() + s4() + '-' + s4();
};

wss.on('connection', function connection(ws, req) {
    ws.id = wss.getUniqueID();

    wss.clients.forEach(function each(client) {
        console.log('Client.ID: ' + client.id);
    });
});

You can also pass parameters directly in the client connection URL:

https://myhost:8080?myCustomParam=1111&myCustomID=2222

In the connection function you can get these parameters and to assign these parameters directly to your ws client:

wss.on('connection', function connection(ws, req) {

    const parameters = url.parse(req.url, true);

    ws.uid = wss.getUniqueID();
    ws.chatRoom = {uid: parameters.query.myCustomID};
    ws.hereMyCustomParameter = parameters.query.myCustomParam;
}