Method check

packages/engine.io/lib/socket.ts:341–346

()

    // we force a polling cycle to ensure a fast upgrade
    const check = () => {
      if ("polling" === this.transport.name && this.transport.writable) {
        debug("writing a noop packet to polling for fast upgrade");
        this.transport.send([{ type: "noop" }]);
      }
    };

    const cleanup = () => {
      this.upgrading = false;