The loading event fires when the document begins loading fonts. Syntax: Use the event name in methods like addEventListener(), or set an event handler property.
This guide explains how to use the Google Fonts API to add fonts to your web pages. You don't need to do any programming. Overview · Specifying font families and... · Optimizing your font requests
FontFaceSet is an interface defined as part of the CSS Font Loading API. It's used to load font faces, and check the status of previously requested fonts.