Haxe

haxelib install colyseus

import io.colyseus.Client;
import io.colyseus.Room;
 
var client = new Client('ws://localhost:2567');

client.joinOrCreate("room_name", [], RoomState, function(err, room) {
    if (err != null) {
        trace("JOIN ERROR: " + err);
        return;
    }
 
    room.state.entities.onAdd(function(entity, key) {
        trace("entity added at " + key + " => " + entity);
 
        entity.onChange(function (changes) {
            trace("entity has been changed");
        });
    })
 
    room.state.entities.onChange(function(entity, key) {
        trace("entity changed at " + key + " => " + entity);
    })
 
    room.state.entities.onRemove(function(entity, key) {
        trace("entity removed at " + key + " => " + entity);
    })
});

room.onStateChange += function(state) {
  // full new state avaialble on 'state' variable
}

room.onMessage("type", function (message) {
  trace(client.id + " received on " + room.name + ": " + message);
});

room.onError += function() {
  trace(client.id + " couldn't join " + room.name);
}

room.onLeave += function() {
  trace(client.id + " left " + room.name);
}

git clone https://github.com/colyseus/colyseus-hx.git
cd colyseus-hx/example/openfl
lime build project.xml html5