BrowserVersionOwn?TypeAs String
Chrome81.0.4044???
Edge86.0.622???
Firefox68.0.0ownfunctionfunction FontFaceSet() { [native code] }
HeadlessChrome81.0.4044???
IE10.0.0???
Safari10.1.2ownfunctionfunction FontFaceSet() { [native code] }

PropertiesChromeEdgeFirefoxHeadlessChromeIESafari
length?? 68.0.0?? 10.0.0
prototype?? 68.0.0?? 10.0.0