Thanks for that.

So really their (FSF/GNU) issue is not with JS at all, but with devs who don’t licence their code under a free software licence? In other words, who enforce the copyright of their own algorithms?

What I also find a bit confusing (inconsistent?) with this stance is that a dev can do a reasonable amount of interesting things with HTML+CSS+SVG (obviously there are limits on the ‘interaction’ side of things), and assumably devs can also licence their HTML+CSS+SVG under whatever licence they wish: so then why pick on JS?