How to use certificate authentification for a websocket in the browser.

I did it with python, also i found many tutorials in doing it with nodejs, but is it possible in the browser with javascript too? I didn't find anything about that.

Here's my working python code(part of it to show what i mean)

import json
import websocket
import ssl

print("Start Websocket")
wsapp = websocket.WebSocketApp("wss://localhost:8080",
                               on_open=on_open,
                               on_message=on_message,
                               on_error=on_error,
                               on_ping=on_ping)

wsapp.run_forever(sslopt={"cert_reqs": ssl.CERT_NONE, "certfile": "private.crt",
                          "keyfile": "private.key", "ssl_context.check_hostname": False})
wsapp.close()