How to change the text of the td using Jquery.?

<table id="demoTable">

                <tr>

                    <td align="left" class="ItemLabel" classname="ItemLabel" style="width: 50%;">Activity class<br>

                        <select class="inputFieldClass" classname="inputFieldClass" id="QA_0-1-71" name="QA_0-1-71">

                            <option value=""><None>option>

                            <option value="15105">First Time Contactoption>

                            <option value="15106">Follow upoption>

                        select>td>

                tr>

            table>

and add script on header

<script type="text/javascript">

        $(document).ready(function () {

            $("#demoTable td").each(function () {

                var t=$(this).html();

                $(this).html(t.replace('Activity class', 'some other name'));              

            });

        });

    script>