I have an aspx page with a webdatetimeedit control on it. How do I get or set the value from JavaScript?

I need to do this:

• get the initial value (from the server) when the page loads,
• save it to a variable,
• let the user edit the date in the control,
• then restore the initial value back into the control when the user hits a "Abandon Edits" button.
• I need to do this with JavaScript because postbacks are so slow on this website.

It works fine with my textboxes and my dropdowns.

Here's my JavaScript code:

<script language="javascript" type="text/javascript">
    var strInitialWebdatetimeeditValue = "";
    var strInitialTextboxValue = "";
   
    function SaveInitialValues()
    {
        strInitialMyDateTimeEditValue = document.getElementById('<%=MyDateTimeEdit.ClientID%>').text;
        strInitialMyTextboxValue = document.getElementById('<%=MyTextbox.ClientID%>').value;
    }
   
    function RestoreInitialValues()
    {
        document.getElementById('<%=MyDateTimeEdit.ClientID%>').value = strInitialMyDateTimeEditValue;
        document.getElementById('<%=MyTextbox.ClientID%>').value = strInitialMyTextboxValue;
    }
</script>

<tr>
 <td>
   <igtxt:webdatetimeedit id="MyDateTimeEdit" runat="server" bordercolor="#000050"
    borderstyle="Solid" borderwidth="1px" usebrowserdefaults="False">
  <ButtonsAppearance>
   <ButtonStyle BackColor="Control" BorderColor="Control" BorderStyle="Solid"
    BorderWidth="1px">
   </ButtonStyle>
   <ButtonHoverStyle BackColor="#B8C0E0" BorderColor="#FFFFFF">
   </ButtonHoverStyle>
   <ButtonPressedStyle BackColor="#8090B0" BorderColor="#FFFFFF">
   </ButtonPressedStyle>
  </ButtonsAppearance>
   </igtxt:WebDateTimeEdit>
 </td>
</tr>

<tr>
 <td>
  <asp:TextBox ID="MyTextbox" TabIndex="3" runat="server" Width="244"></asp:TextBox>
 </td>
</tr>