Seems that I occasionally need to trigger the postback on an UpdatePanel, and invariably I forget between usages.

Since this particular post from Encosia has saved my bacon on more than one occasion, I shall share it here (and for my own future benefit):

Easily refresh an UpdatePanel, using JavaScript | Encosia:

I’ve noticed a lot of discussion lately regarding methods to refresh an UpdatePanel via client script. This is very easy on the server side, of course. You can just call UpdatePanel.Update(). However, on the client side, the most common solutions I’ve been seeing just don’t feel right. Many will advise you to use a hidden button control inside the UpdatePanel, manipulated via button.click(), to trigger a partial postback of the UpdatePanel. While it does work, I never have been able to get past the kludgey nature of that solution.

In a nutshell, we can use the __doPostBack() method:

Luckily, there’s an easy method for triggering a postback targeted at the UpdatePanel: __doPostBack().

As long as the event target of a __doPostBack() call is an async trigger of an UpdatePanel, the ASP.NET AJAX framework will intercept the postback and fire a partial postback instead. For purposes of demonstration, I’m going to add that to the OnClick event of the container div:

<div id="Container" onclick="__doPostBack('UpdatePanel1', '');">

Now, clicking anywhere in the UpdatePanel will trigger a partial postback, targeting the UpdatePanel. Since partial postbacks follow the full page lifecycle, this will fire UpdatePanel1_Load and update the Label’s text.