Also, implementing browsers (or operating systems, or cpus) isn't about needing to write amounts of code that would take a long time write - it's about whether you know the subject area and do you already have a plan/architecture in your head that you are going to create.

>Computers aren't necessarily gigantic corporate undertakings.

I'm not saying it's not possible, there are much stories in HN about guys creating VGA cards or self-made computers, I'm asking for evidence.

I think this code constitutes significant evidence about the background of its author.

> Sometime in the past couple months, there was a link on HN to a project also by one dude, who's implementing a CPU on breadboards, with wires.

Maybe you mean Ben Eater. He has a great Youtube Channel: https://www.youtube.com/channel/UCS0N5baNlQWJCUrhCEo8WlA

Not him, but pretty similar, yes. Here it is: https://news.ycombinator.com/item?id=19393279.

I was mistaken, the CPU is a stock Z80 but the guy implements other parts of a bespoke game console, in microcontrollers.

The Toledo browser Biyubi is claimed to support JS, but I suspect its support may be rather outdated.