In 2007, I had a script on my website that records every click and every mouse move. When my classmates are reading my webpages, I'm watching a video simulation of their mouse moves.

My website doesn't contain any textbox, so there's no personal data except IP address. Nevertheless, I more or less know who's reading my page because every student has a static IP.

Nowadays, I don't collect mouse moves anymore, but I have navigator.sendBeacon() for video playback behavior.