Fractalforums

I managed to cross-compile my mandelbrot-perturbator from C/C++ to Javascript using Emscripten.  It's a bit slow (and can break if you click too quickly, and skips too many series approximation iterations at low zoom levels...) and more of a proof of concept than a useful deep zoomer at this moment in time:

https://mathr.co.uk/mandelbrot/perturbator/

To use it you need a recent Firefox Developer Edition with an additional environment variable set:

JIT_OPTION_asmJSAtomicsEnable=true
Otherwise you'll get a yellow rectangle and this message in the web console log:
asm.js Atomics only enabled in wasm test modeI don't know what the browser development roadmap is for asm.js / web assembly / atomics / etc needed for Emscripten pthreads implementation, so this is all a bit highly experimental at the moment - it'll probably settle down in a few browser versions' time when the standards are all ironed out...