RJS is a great Ruby DSL to write javascript. However, it's so tempting to write RJS directly in the views, and soon the views contain substantial controller knowledge (e.g. link_to_remote, link_to, etc) KRJS attempts to solve that problem by allowing dynamic inclusion of AJAX calls on HTML elements. When a controller defines a method (based on naming convention) that handles a client-side event, the rendering engine will do the wiring automatically - when the event happens, an AJAX call will be made to the controller's method which would ideally reply with RJS and update portions of the document.