These different approaches require porting of existing P4JSAPI applications. This guide explains:
How to port existing code, in particular the syntax of formatting requests. The P4VJS data sent and returned is fully compatible with the formatting that the P4JSAPI expects.
Which P4JSAPI features are not ported to P4VJS. This version of P4VJS does not introduce new features to the API, but it does simplify the hosting of pages and adds more flexibility. For details, see the P4VJS Developer Guide.