[Izkata]

> Still, JavaScript is the most brittle of all front-end web technologies.

I don't think "brittle" is the right word. I get what it's going for, but thinking back to the jquery days where the javascript was driven by events fired from the DOM instead of a framework, it was actually really robust - when something went wrong, instead of the whole page crashing, you'd end up with just one feature not working while everything else was fine.

[mr_toad]

I think the author is referring to things on the client that are outside the developers control, like network issues, script blockers, origin restrictions, firewalls/badly behaved proxy servers, outdated browsers etc.