How to use the isomorphic-ws.CONNECTING function in isomorphic-ws

public disconnect(): void {
    if (!this.socket) {
      throw new Error("Socket undefined. This must be called after connecting.");
    }

    this.clearTimeout();

    switch (this.socket.readyState) {
      case WebSocket.OPEN:
        this.socket.close(1000 /* Normal Closure */);
        break;
      case WebSocket.CLOSED:
        // nothing to be done
        break;
      case WebSocket.CONNECTING:
        // imitate missing abort API
        this.socket.onopen = () => 0;
        this.socket.onclose = () => 0;
        this.socket.onerror = () => 0;
        this.socket.onmessage = () => 0;
        this.socket = undefined;
        if (this.closeHandler) {
          this.closeHandler({ wasClean: false, code: 4001 });
        }
        break;
      case WebSocket.CLOSING:
        // already closing. Let it proceed
        break;
      default:
        throw new Error(`Unknown readyState: ${this.socket.readyState}`);
    }