Method emitWithAck

packages/socket.io/lib/socket.ts:294–310

* Emits an event and waits for an acknowledgement * * @example * io.on("connection", async (socket) => { * // without timeout * const response = await socket.emitWithAck("hello", "world"); * * // with a specific timeout * try { * const response = await socket.t

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

   * @return a Promise that will be fulfilled when the client acknowledges the event
   */
  public emitWithAck<Ev extends EventNamesWithAck<EmitEvents>>(
    ev: Ev,
    ...args: AllButLast<EventParams<EmitEvents, Ev>>
  ): Promise<FirstNonErrorArg<Last<EventParams<EmitEvents, Ev>>>> {
    // the timeout flag is optional
    const withErr = this.flags.timeout !== undefined;
    return new Promise((resolve, reject) => {
      args.push((arg1, arg2) => {
        if (withErr) {
          return arg1 ? reject(arg1) : resolve(arg2);
        } else {
          return resolve(arg1);
        }
      });
      this.emit(ev, ...(args as any[] as EventParams<EmitEvents, Ev>));
    });
  }

  /**
   * @private