Probably Facebook trackers. I noticed a lot of apps (including my own) having major slowness on initial load while they were down. My assumption is it was their tracking code timing out.
It was probably due to the global DNS system being overloaded due to people and apps repeatedly retrying facebook connections. Cloudflare reported 30x normal DNS requests for FB properties.
Well, these days server side api… er Conversions API is the way to go. This way if the user blocks the browser pixel the data can still be acquired for certain events, say a purchase. Google Tag Manager server side has something similar.
Hit F12 on your browser and look at the network traffic. HN only loads a handful of files: the html page, a style sheet, a JavaScript file and a few GIFs for the arrows and faveicon.
The JS is uncompressed and very readable. It only contains logic for site use, no code to call back some other trackers.
A perfect example of site that doesn't need to use client-side analytics to sell ads.
