Asynchronous visual webpart for SharePoint 2013

HI,

How to create asynchronous visual webparts in SharePoint 2013 (VS 2012) . I can see lot of examples for 2010 version, but not for SP 2013.

I have 2 visual webparts, which I want to make it as a asynchronous webpart. One webpart has the code written in Javascript client object model(loads lot of images), another is a server side webpart which has a SPGridview.

Is there any sample code available for SP 2013?

Thanks