Tabris.js is simply the best tool I've found for creating cross-platform mobile apps from a single code base and I've looked at pretty much everything available during the last couple months. The only thing which might be close is React Native. It was next on my list but I got sidetracked by the discovery of Tabris while researching using Material Design with NativeScript. Someone posted a link to it in the comments section of a web page and, due to frustration with NS, I decided to take a look. My initial reaction was that it was too good to be true and anything this promising would be far better known. Luckily for me, their web site makes it really easy to check everything out without installing anything on your computer. It only took about five minutes to be convinced they are for real. Do yourself a favor and check into this incredible tool.
Demos work flawless on galaxy nexus
Great demo Great demo! Works perfect on my HTC One X.
The Tabris 2.0 update brings full support for RAP 3.x.