[thoughtsunifica]

To begin with, by all mean use React, Vue and others. I think they're amazing and got me super excited whenever I deal with them.

userinterface.js was made out of the frustration I went through when I was maintaining multiple Browser Extensions. I wanted it to exploit my existing knowledge of DOM API and JavaScript language. Something that would at least try to befriend CSS, HTML and JS to make them work together in a semantic fashion.

Giving their own world to each of the parts of the UI was for the most part the core aspect of it.

Most of the frameworks you mentionned have their own ecosystem, I find them pretty hard to integrate in contexts such as Browser Extension if you do not wish for a never ending build toolchain.

I think a fair comparison for userinterface.js would be the Web Components API.

I'm glad you're even asking the question, thanks.