I was wondering this as well. My best guess is that they're using some kind of WebSocket proxy server; that's how Emscripten does it: https://emscripten.org/do

I was wondering this as well. My best guess is that they're using some kind of WebSocket proxy server; that's how Emscripten does it: https://emscripten.org/docs/porting/networking.html https://emscripten.org/docs/porting/networking.html