we use C++ for our program developping. So we can use Kripten (https://github.com/kripken/emscripten/wiki) in order to compile from c++ to javascript.
We use standard OpenGL to paint, so with WebGL can be possible if the compiler is as good as I can see with the examples. Did you know if this can be used in this kind of projects? The main handicap can be the performance.