參考文章：
- Real-time Websocket Connection between Sensor Reading ESP8266 and Node.JS Server
- Interface DHT11 DHT22 w/ ESP8266 NodeMCU Using Web Server
- Communication with an ESP8266 (NodeMCU) through Websockets
- ESP8266 Web server with Web Socket to control an LED
- Communication with an ESP8266 (NodeMCU) through Websockets
