What is Realtime Debugger for JS

Question

JavaScript

From now on they demonstrate how the game
works youtu.be/PJlp1YacstQ?t=23m58s
What kind of thing do they have on the host? Mb samopisnoe something, not for everyone?

Answer 1

Where did you see the debugger? I saw only the formatted log.

Answer 2

Obviously, something self-written, there the url is clearly visible.