Method emit

packages/socket.io/lib/broadcast-operator.ts:209–309

* Emits to all clients. * * @example * // the “foo” event will be broadcast to all connected clients * io.emit("foo", "bar"); * * // the “foo” event will be broadcast to all connected clients in the “room-101” room * io.to("room-101").emit("foo", "bar"); * * // with an ack

(
    ev: Ev,
    ...args: EventParams<EmitEvents, Ev>
  )

   * @return Always true
   */
  public emit<Ev extends EventNames<EmitEvents>>(
    ev: Ev,
    ...args: EventParams<EmitEvents, Ev>
  ): boolean {
    if (RESERVED_EVENTS.has(ev)) {
      throw new Error(`"${String(ev)}" is a reserved event name`);
    }
    // set up packet object
    const data = [ev, ...args];
    const packet = {
      type: PacketType.EVENT,
      data: data,
    };

    const withAck = typeof data[data.length - 1] === "function";

    if (!withAck) {
      this.adapter.broadcast(packet, {
        rooms: this.rooms,
        except: this.exceptRooms,
        flags: this.flags,
      });

      return true;
    }

    const ack = data.pop() as (...args: any[]) => void;
    let timedOut = false;
    let responses: any[] = [];

    const timer = setTimeout(() => {
      timedOut = true;

      debug("operation has timed out");
      // @ts-expect-error
      const packetId = packet.id;

      if (packetId !== undefined) {
        this.adapter.nsp.sockets.forEach((socket) => {
          socket.acks.delete(packetId);
        });
      }

      ack.apply(this, [
        new Error("operation has timed out"),
        this.flags.expectSingleResponse ? null : responses,
      ]);
    }, this.flags.timeout);

    let expectedServerCount = -1;
    let actualServerCount = 0;
    let expectedClientCount = 0;

    const checkCompleteness = () => {
      debug(
        "responses: servers: %d / %d ; clients: %d / %d",
        actualServerCount,
        expectedServerCount,