checkLoadedFonts.js

  function checkFonts() {
    document.fonts.onloadingdone = function (fontFaceSetEvent) {
      console.log(
        "🚀 ~ file: default.js ~ line 27 ~ checkFonts ~ fontFaceSetEvent",
        fontFaceSetEvent
      );
      alert(
        "onloadingdone we have " +
          fontFaceSetEvent.fontfaces.length +
          " font faces loaded"
      );
    };
  }

/*
* USAGE: 

  useEffect(() => {
    console.log(checkFonts());
  }, []);

*/