用Django单击按钮后弹出窗口

Question

我试图在用户单击“注册/登录”按钮后弹出一个警报窗口，以显示成功或失败。

if("signup_btn" in request.GET):
    user = request.GET.get("user_name", None);
    pwd = request.GET.get("user_password", None);
    err = checkValidility(user, pwd);

    # signup success
    if(err == 0):
        connect = sqlite3.connect("user.db");
        c = connect.cursor();
        c.execute('''
                  INSERT INTO USER
                  (USER, PASSWD)
                  VALUES({}, {})
                  '''.format(user, pwd)
                  );
        connect.close(); # insert user information into database

        # pop-up window 
        messages.debug(request, "Sign up success."); # try to use messages

        # signup failure
        else:
            messages.debug(request, signup_err[err]); # just error message

    html = get_template("login.html").render();
    return HttpResponse(html);

我的HTML看起来像

<!-- pop up window -->
{% if messages %}
    <script>
        {% for msg in messages %}
            alert('{{ msg.message }}');
        {% endfor %}
    </script>
{% endif %}

但是什么也没发生，有人可以告诉我该怎么做吗？