main.html

<div class="container">
    <div class="row justify-content-center">
        <div class="col-12 col-md-5">
            <button class="btn btn-primary btn-block" id="btnTransmit">Transmit Message</button>
            <button class="btn btn-primary btn-block" id="btnReceive">Receive Message</button>
        </div>
    </div>

    <script type="text/javascript">
        $(document).ready(function () {
            $("#btnTransmit").on("click", function () {
                loadAtSecondFrame("framing.html", "transmit");
            });

            $("#btnReceive").on("click", function () {
                loadAtSecondFrame("framing.html", "receive");
            });
        });
    </script>
</div>