how do we investigate how many times a browser is doing reflows?

Question

Is there a web developer functionality/tool that allows us to know how many times a browser is doing reflows?

basically I want to have some sort of feedback/informa

Answer 1

Sometime after late 2013, the reflow logging is built into Firefox logging.

https://mail.mozilla.org/pipermail/firefox-dev/2013-October/001044.html

In browser console (Tools > Web Developer > Browser Console), in the [CSS] menu, select "Log"