How do send the actual control id of an UpdatePanel to an UpdatePanelAnimationExtender ScriptAction script?

I need to send the actual control id that .NET generates for an U开发者_运维技巧pdatePanel's div to a javascript function. How do I rewrite the ScriptAction line below to accomplish this?

<asp:UpdatePanel ID="update1" runat="server" UpdateMode="Conditional">
    ...
</asp:UpdatePanel>

<cc1:UpdatePanelAnimationExtender runat="server" TargetControlID="update1">
    <Animations>
        <OnUpdating>
            <Parallel duration="0">
                <ScriptAction Script="doSomething(**update1's ID**);" />
            </Parallel>
        </OnUpdating>
        ...
    </Animations>
</cc1:UpdatePanelAnimationExtender>

EDIT:

I would like to have update1.UniqueId be placed in doSomething's parameters.

EDIT:

The following fails:

<ScriptAction Script="alert('<%= update1.ClientID %>');" />

With

 Exception type: System.Web.HttpParseException
 Exception message: The 'Animations' property of 'cc1:UpdatePanelAnimationExtender' does not allow child objects.

Have you tried to use its ClientID?

Script="doSomething('<%= update1.ClientID %>');"

According to your updated question: add this ClientID as a javascript variable at the top of the page. Then you can access it from your js-function.

Something like this:

<script type="text/javascript">  var update1ClientID = '<%= update1.ClientID %>';</script>

and then:

Script="doSomething('' + update1ClientID );"

If this also doesn't work, try to use the same approach but from Codebehind(Page_Load)

ScriptManager.GetCurrent(Me.Page).RegisterClientScriptBlock(Me, Me.GetType, "update1ClientID", "var update1ClientID='" & Me.update1.ClientID & "';", True)

<ScriptAction Script="doSomething('<%=update1.ClientID %>');" />

** Edit *

To add to Tim's solution, if you have more than one custom control per page, iterate through the page controls and add a register script for each control that is of the type of your custom control.