You might want to check out https://github.com/necolas/react-native-web - that has implementations for a lot of the React Native primitives on the web, to make code-sharing easier.
Re:Angular 2 – Best Practises
by Secretmapper on Monday June 27, 2016 @12:35PM
(#11987314)
Have you tried it recently? I don't think I've had this problem with recent versions.
At least with Angular/Ionic you can directly share UI code between the two as its all HTML and CSS.
Still, I really enjoy working with React and React Native because I it's one API and mental model to learn.