[squeaky-clean]

React Native [0]. Your view-specific code still has to be done per-platform, but your core logic can be shared, and all of it is written with Javascript using React as the framework. The JS creates and controls native elements, with the native parts mostly abstracted away.

[0] https://facebook.github.io/react-native/

[marcusr]

Exactly this, made even simpler by the naming scheme that lets you have iOS and Android versions of the same component.

[mbrock]

You can write much view code in a way that abstracts over the DOM/Native platform, too, using standard abstraction techniques.