Method emit

packages/socket.io-client/lib/socket.ts:410–459

* Override `emit`. * If the event is in `events`, it's emitted normally. * * @example * socket.emit("hello", "world"); * * // all serializable datastructures are supported (no need to call JSON.stringify) * socket.emit("hello", 1, "2", { 3: ["4"], 5: Uint8Array.from([6]) });

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

   * @return self
   */
  public emit<Ev extends EventNames<EmitEvents>>(
    ev: Ev,
    ...args: EventParams<EmitEvents, Ev>
  ): this {
    if (RESERVED_EVENTS.hasOwnProperty(ev)) {
      throw new Error('"' + ev.toString() + '" is a reserved event name');
    }

    args.unshift(ev);

    if (this._opts.retries && !this.flags.fromQueue && !this.flags.volatile) {
      this._addToQueue(args);
      return this;
    }

    const packet: any = {
      type: PacketType.EVENT,
      data: args,
    };

    packet.options = {};
    packet.options.compress = this.flags.compress !== false;

    // event ack callback
    if ("function" === typeof args[args.length - 1]) {
      const id = this.ids++;
      debug("emitting packet with ack id %d", id);

      const ack = args.pop() as (...args: any[]) => void;
      this._registerAckCallback(id, ack);
      packet.id = id;
    }

    const isTransportWritable = this.io.engine?.transport?.writable;
    const isConnected = this.connected && !this.io.engine?._hasPingExpired();

    const discardPacket = this.flags.volatile && !isTransportWritable;
    if (discardPacket) {
      debug("discard packet as the transport is not currently writable");
    } else if (isConnected) {
      this.notifyOutgoingListeners(packet);
      this.packet(packet);
    } else {
      this.sendBuffer.push(packet);
    }

    this.flags = {};

    return this;
  }

  /**
   * @private