function sendNickname() {
        var text = nicknameArea.value;
        nicknameArea.value = "";
        websocket.send("nickname:" + text);

        if (text != null){
            document.getElementById("nicknameArea").value = "Twój nick: " + text;
            document.getElementById("nicknameArea").disabled = true;
            document.getElementById("messageArea").disabled = false;
        } else {
            document.getElementById("messageArea").disabled = true;
        }
    }