A web browser application executing on a computing device receives, in response to a request for a web page, (i) a set of declarative markup data that defines a hierarchical arrangement of components of the web page and (ii) a set of scripts that defines structure and operation of the components. The declarative markup data and scripts cooperatively define data bindings between components of the page. Further the scripts can be changed from time to time, so that when the web browser application subsequently requests the same web page, the web browser application may receive in response the same declarative markup data but a different set of scripts that still supports the same data bindings between the components of the page.