Yes. Particularly it's those little badges that let you share some content or other on the social media site of your choice. I'm under the impression that whether you click them or not, they are phoning home to Facebook about your behavior.
So it's not hidden in react itself but rather in the constructed-on-page-load-and-hard-to-disable-just-parts-of space which react creates.
I'll confess to not having merely read about this skulduggery and not analyzed it myself. But it certainly explains why Facebook open sourced react and also why those things are everywhere. Is there a better explanation?
