function loggedIn() {
    $.ajax({
        type: "GET",
        url: "/api/auth",
        success: function (a) {
            if (a.success == "true") {
                return true;
            } else {
                return false;
            }
        }
    });
}

<script type="text/javascript">
    $(function() {
        if (loggedIn() == true) {
            $('#send-to-user-btn').css('display', 'block');
            $('#sign-in-button-btn').css('display', 'none');
            $('#login-bar-my').css('display', 'none');
        }
    });
</script>