Actually it seems that the second worst in JavaScript (when executing their example) is Chrome?

User robko here https://news.ycombinator.com/item?id=19167078 measured the code on node.js, and node.js is based on Chrome's V8 and he measured 1.5 sec vs article author's of around 2.7s, so it would seem that robko has some almost twice as fast CPU, and the other two (fast) JavaScripts are under 500 ms, and the slowest is 8 seconds, so V8 of Chrome remains the only candidate for the second worst performing of their example.

I wish they had at east posted a browser-runnable version of their test so we could see for ourselves which browser is which, or compare JS vs WASM on our own systems. (On this type of code, I'd expect Safari to be the fastest, not Chrome.)

See my "minimal" C++ translation in my other post here. There's not much to add. For JavaScript start with their code, but add the allocation, just replace allocations with var a = new Uint32Array(height * width); and b the same. Add the timing (1), put in HTML and you're done. It's easy, just a few minutes for anybody who works with that (and this site should be filled with the competent developers AFAIK).

1) https://developer.mozilla.org/en-US/docs/Web/API/Performance