How to move a single page webapp into Express?

[Mordillo]

I have a single-page webapp (a client built with its javascript engines , with a jsp proxy backend that interfaces to a RDBMS. Client and jsp proxy are connected via ajax calls) that i would migrate to Express to build a full javascript stack (javascript client with REST calls and a Node interface to the RDBMS). How do i do this migration? How can I integrate the html/javascript client (unaltered as a static page with its javascript engine) into Express and add the REST calls?