this is more of a spike towards https://www.npmjs.com/package/chrome-serialport - connecting the http module with long polling is not too difficult for reading. otherwise sockets are probably cleaner. for the asm.js approach, what blocking points did you experience?
We did another aproach, because it was like 8 years ago, we decided to try to implement a emolator for the microcontroller in ActionScript, but that resulted really too hard.