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How to influence roomId for new room?

  • Is there a way to choose or influence what the roomId will be when a new instance of a room is created?

    For example, if I do something like

    gameServer.register("chat", ChatRoom).then((handler) => {
        on("create", (room) => console.log("room created:", room.roomId)).
        on("dispose", (room) => console.log("room disposed:", room.roomId)).
        on("join", (room, client) => console.log(, "joined", room.roomId)).
        on("leave", (room, client) => console.log(, "left", room.roomId));

    and set max clients to 2, when a new client joins the "chat" room then a new room instance gets created with a unique roomId. That's great, but the room IDs are not so friendly and so if I want one player to give his room ID to another so they can play in the same game, I would like friendlier room IDs. Can the server (or better yet the client) somehow influence the room ID either by choosing it directly or providing a suffix or prefix?


  • administrator

    hey @cmdt-ed, you can override the roomId during onInit():

    // server-side
    onInit(options) {
      this.roomId = options.roomId;
    // client-side
    var room = client.join("chat", { roomId: "hello" })

    Keep in mind that making sure these values are unique is in your hands this way.

  • Thanks. That sounds great. Since javascript is single-threaded, I should just be able to check the proposed roomId on the server, right?

    Could you point me to the property or method to get the room IDs on the server?


  • Looking at the code it seems like maybe I should look at this.presence.smembers(roomName) to get a list of all rooms (not just the available ones). Does that sound like the right thing to check to make sure I am not creating a roomId which already exists?

  • administrator

    Hey @cmdt-ed, it's not ideal but you can use that. The Presence API doesn't currently support sismember - which is better for checking that, I'd appreciate if you can send me a pull-request adding it!

    There's only two Presence implementations now, both can implement this method:

    • LocalPresence: for single-threaded environments link
    • RedisPresence: for multi-threaded environments link


  • OK, I'll look into doing that. I don't have much experience with redis, promises, async and even javascript but I'll see what I can do.