Technologies involved:

1. ASP.NET Web-forms
2. Javascript (jQuery for instance)

Case

To make it clearer let's give the Stackoverflow Users list as an example. This list can be manipulated at client-side. I can search, page and so forth. So obviously we would need to call jQuery.ajax to retrieve the HTML of each page given a search. Alright. Now this leaves me with the first question:

What is the best way to render the response for the jQuery.ajax at server-side? I can't use templates I suppose, so the most obvious solution I think is to create the HTML tags as server-controls and render them as the result of an ASHX request? Is this is best approach?

Nice. That solved we have yet another problem:

When the user first enters the Authors List the first list page should already come from the server completely rendered alright? Of course we could render the first page as well as an ajax call but I don't think it's better. This time I CAN use templates to render the list but this template couldn't be reused in case 1. What do I do?

Now the final question:

Now we have 2 rendering strategies: 1) Client and 2) Server. How do I reuse code for the 2 renderings?

What are the best pratices for solving these problems?