WebAssembly code can talk to the rest of your JS (and therefore asm.js) code, right?

So PyPy.js runs Python in the browser via asm.js:

http://pypyjs.org/

https://github.com/pypyjs/pypyjs

Livebook uses PyPy.js to make a Jupyter-like notebook that runs entirely in the browser, and includes pandas:

https://livebook.inkandswitch.com

https://github.com/inkandswitch/livebook

And random plug for Observable in case you haven't seen it, a Jupyter-like Javascript environment, completely in the browser:

https://observablehq.com