I know there's been a ton of work done of Parsoid lately. This is great, and the amount of effort that's gone into this functionality is really appreciated. It's clear that Parsoid is the way of the future, but the documentation of how you get a Parsoid parse tree via an AP call isI kind of confusing.
I found https://www.mediawiki.org/wiki/Parsoid/API https://www.mediawiki.org/wiki/Parsoid/API, which looks like it's long out of date. The last edit was almost 2 years ago. As far as I can tell, most of what it says is obsolete, and refers to a series of /v3 routes which don't actually exist.
I also found https://en.wikipedia.org/api/rest_v1/#/Page%20content <https://en.wikipedia.org/api/rest_v1/#/Page content>, which seems more in line with the current reality. But, the call I was most interested in, /page/data-parsoid/{title}/{revision}/{tid}, doesn't actually respond (at least not on en.wikipedia.org http://en.wikipedia.org/).
Eventually, I discovered (see this thread https://en.wikipedia.org/w/index.php?title=Wikipedia:Village_pump_(technical)&oldid=976731421#Parsing_wikitext_in_javascript?), that the way to get a Parsoid parse tree is via the https://en.wikipedia.org/api/rest_v1/page/html/ https://en.wikipedia.org/api/rest_v1/page/html/ route, and digging the embedded JSON out of data-mw fragments scattered throughout the HTML. This seems counter-intuitive. And kind of awkward, since it's not even a full parse tree; it's just little snippets of parse trees, which I guess correspond to each template expansion?
So, taking a step backwards, my ultimate goal is to be able to parse the wikitext of a page and discover the template calls, with their arguments. On the server side, I'm doing this in Python with mwparserfromhell, which is fine. But now I need to do it on the client side, in browser-executed javascript. I've looked at a few client-side libraries, but if Parsoid really is ready for prime time, it seems silly not to use it, and it's just a question of finding the right API calls.