How to add payload on connection init

[khuongtp]

Hello. Can somebody tell me how to add the payload on connection init like in this playground

I tried doing like this but not working

  const [res] = useSubscription<ChatSubscription, any, ChatSubscriptionVariables>({
    query: chatDoc,
    variables: { roomId: "1" },
    context: {
      fetchOptions: { headers: { Authorization: "123123" } },
    },
  });