Can I use this repo to detect websocket http request header: sec-websocket-key?

[zydjohnHotmail]

Hello:
I need some code sample on how to detect WebSocket (wss) requests.
Basically, I can visit this URL with Chrome: https://www.websocket.org/echo.html
And click on “Connect” button to connect with the WebSocket server: wss://echo.websocket.org
Then type something in the message box, or using the default text in the message box “Rock it with HTML5 WebSocket”, then click on “Send” button, then I can see the messages on the “log” textbox, like this:
CONNECTED
SENT: Rock it with HTML5 WebSocket
RECEIVED: Rock it with HTML5 WebSocket
Then open Developer Tools from Chrome, on “Network” tab, I can see there is only one WS (WebSocket) request with the following headers:
Request URL:
wss://echo.websocket.org/?encoding=text

1. Request Method:
   GET
2. Status Code:
   101 Web Socket Protocol Handshake
   I can use Chrome developer tools to convert the WebSocket request to Node.JS fetch:
   fetch("wss://echo.websocket.org/?encoding=text", {
   "headers": {
   "accept-language": "en-US,en;q=0.9,fr;q=0.8,nl;q=0.7,zh-CN;q=0.6,zh;q=0.5,zh-TW;q=0.4",
   "cache-control": "no-cache",
   "pragma": "no-cache",
   "sec-websocket-extensions": "permessage-deflate; client_max_window_bits",
   "sec-websocket-key": "PVg+yYO5Q3EVgtPLLV2QXQ==",
   "sec-websocket-version": "13"
   },
   "body": null,
   "method": "GET",
   "mode": "cors"
   });
   Let me know how I can use this repo to get all the headers, actually, there is only one header I need to get is: "sec-websocket-key": "PVg+yYO5Q3EVgtPLLV2QXQ=="

In my real-world job, I have to detect webscoket request from one specific web site. Using Chrome devtools, I can see that the web page uses rather complicated JavaScript to generate a websocket request, and sends it to the server. I want to write some kind of browser extension to detect the websocket request headers, actually, I only need this header: "sec-websocket-key".
Please advise,
Thanks,