UpdatePanel update without trigger button

I have an UpdatePanel with ContentTemplate specified. When page loads, user can do some AJAX work in other part of the page. Then, after that work is finished, I would like to update only content inside UpdatePanel, but without pressing any buttons etc. I should be done automatically using JavaScript when previously started AJAX work finishes. How to do it without manual clicking on the trigger button?

EDIT:

Ok, I've followed that _doPostBack rule, and whole page is posted.

    <as开发者_Go百科p:UpdatePanel ID="panelAttachments" runat="server">
        <ContentTemplate>
    ........
        </ContentTemplate>
    </asp:UpdatePanel>
    <input type="text" name="test" onchange="__doPostBack('<%=panelAttachments.UniqueID %>',''); return false;" />
</td>

Thanks, Pawel

To refresh an update panel from javascript:

__doPostBack(updatePanelUniqueID,'');

The first parameter is the UniqueID (not CientID) of the UpdatePanel.The 2nd parameter is optional arguments you can pass which will be available to your server code. Both are stored in hidden form fields by ASP.NET, you can access them in codebehind:

Request.Form["__EVENTTARGET"];
Request.Form["__EVENTARGUMENT"];

But if you just want to refresh a panel and don't need to pass any additional info from the client, you can ignore then 2nd argument.

If you look at the HTML generated by ASP.NET for an async postback control, you'll see it's exactly this.