(JUCE-based) audio applications in web browser?

I read the stuff about NPAPI and ActiveX browser plugins, but just noticed that Chrome will be dropping NPAPI support soon, so I'm actaully wondering: what should be used nowadays to build a web browser application using an existing (or new) C++ JUCE codebase? (if still possible at all)

I read NaCl is Google's alternative, but then that's only for Chrome.

Any ideas about what to use for browser-based apps that can run C++ code?
Or is low-level audio support in HTML5 now good enough and supported in all the latest major browsers (Chrome, IE, Safari, FireFox) to go that route?



I think  "asm.js"/emscripten will be used in the future, for this kind browser apps, because its downwards compatible... 

Something like this exists for QT 



Would definitely love to get juce ported to emscripten - that'd be really interesting to play with.

Not sure, but wouldn't a system like asm.js/emscripten or Duetto have problems with accessing the audio hardware (or probably many other parts of the JUCE framework that use native calls)?

It would be great of course if you can have a native application in C++, that can then be "exported" to an app that can run in the browser. This is what Unity provides, where you can have the project built for Windows/MacOSX, and also for their webplayer so you can run it in the browser. But that only works with C# code, not C++ I believe.