On the technical side, anyone know how their browser extension to save webpages.. works?

I'm writing a personal reader / reference tool. More of a knowledge base than a formal reference tool, but i want similar functionality, and so i've been researching ways to locally archive web pages to cite in notes. To save effort, i was trying to reuse existing methods in Reader-like libraries. The best i found so far, i think, is Telegram's library of "Instant View" parsers. A community managed set of scrape instructions basically, XPath and whatnot, that i could write an implementation for and - in theory - support everything Telegram does.

This is a fair bit of work though. I debated instead simply saving the whole webpage, but that may require saving the JS and i really don't want to execute JS as part of the citation.

Anything i might be missing here? Instant View is the only community managed format for scraping i've seen, i'm surprised this isn't more commonly outsourced to communities for Reader modes and whatnot