I don't think v86 [1] is based on qemu, but it's a javascript (well javascript + rust->wasm) virtual PC. Not my project, it's super lovely for hobby os demos though. (And they've taken a couple of my PRs!)

[1] https://copy.sh/v86/ https://github.com/copy/v86

It seems to be using 'v86' by copy.

[0]: https://github.com/copy/v86