Web Font Loader provides an event system that developers can hook into. It gives you notifications of the font loading sequence in both CSS and JavaScript.

loading - This event is triggered when all fonts have been requested.

active - This event is triggered when the fonts have rendered.

inactive - This event is triggered when the browser does not support linked fonts or if none of the fonts could be loaded.

fontloading - This event is triggered once for each font that's loaded.

fontactive - This event is triggered once for each font that renders.

fontinactive - This event is triggered if the font can't be loaded.