Websocket connection fails in jupyterlab extension

JupyterLab extensions
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In my server extension I have following websocket handler using tornado websockets:

class EchoWebSocket(tornado.websocket.WebSocketHandler):
def open(self):
    print("WebSocket opened")

def on_message(self, message):
    self.write_message(u"You said: " + message)
    # self.stream_logs()

def on_close(self):
    print("WebSocket closed")

I could connect to this websocket from an python client side code given here:

    import asyncio
    import websockets

    async def connect_to_websocket(uri):
        async with websockets.connect(uri) as websocket:
            await websocket.send("kdkdkd")
            while True:
                # Receive message from the WebSocket server
                message = await websocket.recv()
                print(f"Received message: {message}")
    
             
    
    async def main():
        uri = "ws://localhost:8889/myextension/echows"  # WebSocket server URI
        await connect_to_websocket(uri)

    if __name__ == "__main__":
        asyncio.create_task(main())

but when I try to connect to it using javascript based client code it throws error VM449:3 WebSocket connection to ‘ws://localhost:8889/myextension/echows/’ failed . Note that I want trigger this connection in my jupyterlab extension javscript client code goes as:

async function connectToWebSocket(uri) {
      try {
        const connection = await new WebSocket(uri);

connection.onmessage = (event) => {
  console.log(`Received message: ${event.data}`);
};

connection.onerror = (error) => {
  console.error('WebSocket error:', error);
};

await connection.send("kdkdkd");

while (connection.readyState === WebSocket.OPEN) {
  // Receive messages and handle them appropriately (e.g., print or process)
  const message = await connection.receive();
  console.log(`Received message: ${message}`);
}
      } catch (error) {
console.error('Connection error:', error);
      }
    }

    const uri = "ws://localhost:8889/myextension/echows/"; 

    connectToWebSocket(uri);

I cannot figure out what am I doing wrong in js code although everything working while connecting using python. I’m open to any other suggestion to develop websocket based jupyterlab extension. I’m stuck here for few days now so any help would be appreciated.