connect() {
    if (this.connected)
      return this;
    this.subEvents();
    if (!this.io["_reconnecting"])
      this.io.open();
    if ("open" === this.io._readyState)
      this.onopen();
    return this;
  }
"Opens" the socket.

@example
const socket = io({
  autoConnect: false
});

socket.connect();