in content/lib/paho-mqtt.js [983:1005]
ClientImpl.prototype.disconnect = function () {
this._trace("Client.disconnect");
if (this._reconnecting) {
// disconnect() function is called while reconnect is in progress.
// Terminate the auto reconnect process.
this._reconnectTimeout.cancel();
this._reconnectTimeout = null;
this._reconnecting = false;
}
if (!this.socket)
throw new Error(format(ERROR.INVALID_STATE, ["not connecting or connected"]));
wireMessage = new WireMessage(MESSAGE_TYPE.DISCONNECT);
// Run the disconnected call back as soon as the message has been sent,
// in case of a failure later on in the disconnect processing.
// as a consequence, the _disconected call back may be run several times.
this._notify_msg_sent[wireMessage] = scope(this._disconnected, this);
this._schedule_message(wireMessage);
};