Client side & server side at the same event (onselectedindexchanged)

Question

I have this drop down list. is it possible to call a javascript function and the server side function at the same time from the onselectedindexchanged event?

<asp:DropDownList ID="drpPartGroup" 
                  runat="server" 
                  Height="19px" 
                  Width="169px" 
                  AutoPostBack="True" 
                  onselectedindexchanged="drpPartGroup_SelectedIndexChanged">
</asp:DropDownList>

Thanks.

Answer 1

I think this might help. I had something similar with a search form that had a couple of related DropDownLists in an UpdatePanel. A reset button was wired to a JavaScript function which cleared all text fields, etc on the client side. I also needed to reset the related DropDownLists so that a default value was selected for the first DropDownList and the related items were updated in the second DropDownList based on the default value.

Basically, my client-side JavaScript function reset all the fields, including the first DropDownList and then called the .onchange() event on the first DropDownList.

document.getElementById('yourDropDownListClientID').onchange();

Answer 2

You need to develop an API on the server-side and use AJAX to communicate back with it (look into guidelines for RESTful APIs) at the same time you are firing the client-side function. JavaScript can't straight up ask the server to execute a function.

Drop down lists are a bit too dynamic for a solution like this though, I can't think of a way to do anything involving server-side communication with a select box that won't lead to terrible UX. You might want to rethink whatever you are doing entirely.

Answer 3

Yes, but you must handle the postback manually...

See this article which covers this extremely well. http://msdn.microsoft.com/en-us/library/aa479302.aspx