Another major benefit (of emscripten too) is that is you have significant non-presentation client-side logic, it can be shared between iOS, Android, and the Web

Another major benefit (of emscripten too) is that is you have significant non-presentation client-side logic, it can be shared between iOS, Android, and the Web. For example take something like Dropbox's Carousel architecture, which shares the client side cache, date model, and sync client between iOS and Android via a C++ library. Something like Cheerp or Emscripten allows you to also use this same library on the web.